mthmulders commented on code in PR #759:
URL: https://github.com/apache/maven-site/pull/759#discussion_r2051417312


##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.
+* This guide does not contain information about how to update plugins to use 
the new Maven 4 plugin API.
+  It is planed to create a separate guide for this.

Review Comment:
   ```suggestion
     It is planned to create a separate guide for this.
   ```
   



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features

Review Comment:
   ```suggestion
   3. Introduce optional Maven 4 features
   ```
   



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.
+* This guide does not contain information about how to update plugins to use 
the new Maven 4 plugin API.
+  It is planed to create a separate guide for this.
+
+## Table of content
+
+<!--MACRO{toc|fromDepth=2|toDepth=4}-->
+
+## Prerequisites
+
+This guide assumes that your environment and project meets the following 
prerequisites.
+If they don't fulfill them already, please put effort into meeting them, 
before continuing with this guide.
+
+### Use latest version of Maven 3.9
+
+This guide assumes that the project to be migrated was successfully built 
using the [latest version of Maven 3](/docs/history.html).
+
+### Upgrade plugins to their latest Maven 3 version
+
+Similar to the previous prerequisite, the guides assumes that you are using 
the latest Maven 3 plugin version of all your plugins.
+
+Do not upgrade to a plugin version, which requires Maven 4!
+Be aware of this, if you use tools that can automate updates.
+
+You can use the [versions-maven-plugin's `display-plugin-updates` 
goal][versionpluginupdate], to see which are the latest available versions of 
the plugins you use.
+
+The following example shows the output of the Versions Maven Plugin in a 
project using the outdated version 3.12.0 of the maven-compiler-plugin.
+As you can see, it shows that with version 3.14.0 there is a Maven 3 
compatible update, while the versions 4.0.0-beta-1 and 4.0.0-beta-2 require 
Maven 4 versions.
+
+```
+[INFO] The following plugin updates are available:
+[INFO]   maven-compiler-plugin ............................ 3.12.0 -> 3.14.0
+[INFO]
+[INFO] All plugins have a version specified.
+[INFO]
+[INFO] Project requires minimum Maven version for build of: 3.9
+[INFO] Plugins require minimum Maven version of: 3.6.3
+[INFO]
+[INFO] No plugins require a newer version of Maven than specified by the pom.
+[INFO]
+[INFO] Require Maven 4.0.0-beta-3 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-1
+[INFO]
+[INFO] Require Maven 4.0.0-rc-2 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-2
+```
+
+## Required changes
+
+You need to do the following steps to be able to use Maven 4.
+
+### Upgrade build environment to support Java 17
+
+Maven 4 requires Java 17 to be run.
+This means the build environment (locally but also your CI environment) needs 
to provide a JDK that supports Java 17.
+Either install one to your machine or use a container providing one.
+
+**Note**: Maven 3 can also use executed with Java 17.
+So you should prepare your build environment as soon as possible to have a 
solid, project independent base for further migration.
+
+### Install and use Maven 4
+
+After you have upgraded your build environment to support Java 17, you also 
need to provide Maven 4.
+See the information [where to download](/download.cgi) and [how to 
install](/install.html) Maven 4 for further information.
+
+Places where you might have to configure Maven 4 usage aside installation:
+* [Maven Wrapper](/wrapper/index.html)'s `maven-wrapper.properties` file.
+* [Required Maven version](/enforcer/enforcer-rules/requireMavenVersion.html) 
rule of the Maven enforcer plugin.
+* Your own CI/CD configuration scripts or pipelines.
+
+### Update plugins to Maven 4 version
+
+If there is a dedicated Maven 4 version for used plugins, you should update to 
such a version.
+You can use the [Versions Maven Plugin's `display-plugin-updates` 
goal][versionpluginupdate] to check for updates.
+
+**Note**: While Maven 4.0.0 aims to support all Maven 3.9 compatible plugins, 
this can not be guaranteed for custom plugins which use outdated plugin API 
methods.
+
+## Troubleshooting and required changes if situation applies
+
+The following changes are in general not required by all projects, but might 
apply to yours.
+
+### Fix plugin misconfigurations
+
+There are several misconfigurations in the project's POM declaration that 
result in warnings when using Maven 3.9.
+While your build should not throw any warnings at all, the following ones 
needs to be fixed as they will fail the build in Maven 4.
+
+**Notes**:
+* The [plugin configuration 
guide](/guides/mini/guide-configuring-plugins.html) contains general 
information, how plugins are correctly declared and configured.
+* For analysing wrong build behavior, it might help to use the new 
`--fail-on-severity` parameter, paired with `WARN` as an argument, to fail your 
build when a warning occur.
+
+#### Duplicate plugin declaration
+
+A plugin must only be declared once.
+Defining it multiple times, results the following log message.
+
+> 'build.plugins.plugin.(groupId:artifactId)' must be unique but found 
duplicate declaration of plugin [plugin-name] ...
+
+To fix this, remove the duplicated configuration.

Review Comment:
   Wouldn't it make more sense to write something like "merge the plugin 
declarations"?



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.
+* This guide does not contain information about how to update plugins to use 
the new Maven 4 plugin API.
+  It is planed to create a separate guide for this.
+
+## Table of content
+
+<!--MACRO{toc|fromDepth=2|toDepth=4}-->
+
+## Prerequisites
+
+This guide assumes that your environment and project meets the following 
prerequisites.
+If they don't fulfill them already, please put effort into meeting them, 
before continuing with this guide.
+
+### Use latest version of Maven 3.9
+
+This guide assumes that the project to be migrated was successfully built 
using the [latest version of Maven 3](/docs/history.html).
+
+### Upgrade plugins to their latest Maven 3 version
+
+Similar to the previous prerequisite, the guides assumes that you are using 
the latest Maven 3 plugin version of all your plugins.
+
+Do not upgrade to a plugin version, which requires Maven 4!
+Be aware of this, if you use tools that can automate updates.
+
+You can use the [versions-maven-plugin's `display-plugin-updates` 
goal][versionpluginupdate], to see which are the latest available versions of 
the plugins you use.
+
+The following example shows the output of the Versions Maven Plugin in a 
project using the outdated version 3.12.0 of the maven-compiler-plugin.
+As you can see, it shows that with version 3.14.0 there is a Maven 3 
compatible update, while the versions 4.0.0-beta-1 and 4.0.0-beta-2 require 
Maven 4 versions.
+
+```
+[INFO] The following plugin updates are available:
+[INFO]   maven-compiler-plugin ............................ 3.12.0 -> 3.14.0
+[INFO]
+[INFO] All plugins have a version specified.
+[INFO]
+[INFO] Project requires minimum Maven version for build of: 3.9
+[INFO] Plugins require minimum Maven version of: 3.6.3
+[INFO]
+[INFO] No plugins require a newer version of Maven than specified by the pom.
+[INFO]
+[INFO] Require Maven 4.0.0-beta-3 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-1
+[INFO]
+[INFO] Require Maven 4.0.0-rc-2 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-2
+```
+
+## Required changes
+
+You need to do the following steps to be able to use Maven 4.
+
+### Upgrade build environment to support Java 17
+
+Maven 4 requires Java 17 to be run.
+This means the build environment (locally but also your CI environment) needs 
to provide a JDK that supports Java 17.
+Either install one to your machine or use a container providing one.
+
+**Note**: Maven 3 can also use executed with Java 17.
+So you should prepare your build environment as soon as possible to have a 
solid, project independent base for further migration.
+
+### Install and use Maven 4
+
+After you have upgraded your build environment to support Java 17, you also 
need to provide Maven 4.
+See the information [where to download](/download.cgi) and [how to 
install](/install.html) Maven 4 for further information.
+
+Places where you might have to configure Maven 4 usage aside installation:
+* [Maven Wrapper](/wrapper/index.html)'s `maven-wrapper.properties` file.
+* [Required Maven version](/enforcer/enforcer-rules/requireMavenVersion.html) 
rule of the Maven enforcer plugin.
+* Your own CI/CD configuration scripts or pipelines.
+
+### Update plugins to Maven 4 version
+
+If there is a dedicated Maven 4 version for used plugins, you should update to 
such a version.
+You can use the [Versions Maven Plugin's `display-plugin-updates` 
goal][versionpluginupdate] to check for updates.
+
+**Note**: While Maven 4.0.0 aims to support all Maven 3.9 compatible plugins, 
this can not be guaranteed for custom plugins which use outdated plugin API 
methods.
+
+## Troubleshooting and required changes if situation applies
+
+The following changes are in general not required by all projects, but might 
apply to yours.
+
+### Fix plugin misconfigurations
+
+There are several misconfigurations in the project's POM declaration that 
result in warnings when using Maven 3.9.
+While your build should not throw any warnings at all, the following ones 
needs to be fixed as they will fail the build in Maven 4.
+
+**Notes**:
+* The [plugin configuration 
guide](/guides/mini/guide-configuring-plugins.html) contains general 
information, how plugins are correctly declared and configured.
+* For analysing wrong build behavior, it might help to use the new 
`--fail-on-severity` parameter, paired with `WARN` as an argument, to fail your 
build when a warning occur.
+
+#### Duplicate plugin declaration
+
+A plugin must only be declared once.
+Defining it multiple times, results the following log message.
+
+> 'build.plugins.plugin.(groupId:artifactId)' must be unique but found 
duplicate declaration of plugin [plugin-name] ...
+
+To fix this, remove the duplicated configuration.
+
+### Replace removed directory properties
+
+Maven 4 introduces new public properties dedicated to point to the root and 
top directory of (multi-subproject) project.
+You can now use `${project.rootDirectory}`, `${session.topDirectory}`, 
`${session.rootDirectory}` when declaring paths.
+See the [Maven Model Builder interpolation 
reference][modelbuilderinterpolation] for more details.
+
+At the same time, several (especially internal) properties are deprecated or 
removed.
+This includes the following properties:
+* `executionRootDirectory`
+* `multiModuleProjectDirector`
+
+### Replace conceptional `pre-` and `post-` lifecycle phases
+
+In Maven 3 some lifecycle phases also had conceptional `pre-` and `post-` 
phases, but they were not available for all phases.
+In Maven 4 those phases are removed in favor of new `before:` and `after:` 
phases, available for all lifecycle phases.
+
+## Optional changes and features
+
+### Changed default values
+
+#### Install / deploy at end of build

Review Comment:
   ```suggestion
   #### Install / deploy at end of build (breaking change)
   ```
   
   Given that many people rely on the default value being what they want, we 
should mention that the default changes. This potentially breaks their use case.



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.

Review Comment:
   ```suggestion
   * It is planned to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.
   ```
   



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.
+* This guide does not contain information about how to update plugins to use 
the new Maven 4 plugin API.
+  It is planed to create a separate guide for this.
+
+## Table of content
+
+<!--MACRO{toc|fromDepth=2|toDepth=4}-->
+
+## Prerequisites
+
+This guide assumes that your environment and project meets the following 
prerequisites.
+If they don't fulfill them already, please put effort into meeting them, 
before continuing with this guide.

Review Comment:
   ```suggestion
   If they don't, please make sure they do before continuing with this guide.
   ```
   



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.
+* This guide does not contain information about how to update plugins to use 
the new Maven 4 plugin API.
+  It is planed to create a separate guide for this.
+
+## Table of content
+
+<!--MACRO{toc|fromDepth=2|toDepth=4}-->
+
+## Prerequisites
+
+This guide assumes that your environment and project meets the following 
prerequisites.
+If they don't fulfill them already, please put effort into meeting them, 
before continuing with this guide.
+
+### Use latest version of Maven 3.9
+
+This guide assumes that the project to be migrated was successfully built 
using the [latest version of Maven 3](/docs/history.html).
+
+### Upgrade plugins to their latest Maven 3 version
+
+Similar to the previous prerequisite, the guides assumes that you are using 
the latest Maven 3 plugin version of all your plugins.
+
+Do not upgrade to a plugin version, which requires Maven 4!
+Be aware of this, if you use tools that can automate updates.
+
+You can use the [versions-maven-plugin's `display-plugin-updates` 
goal][versionpluginupdate], to see which are the latest available versions of 
the plugins you use.
+
+The following example shows the output of the Versions Maven Plugin in a 
project using the outdated version 3.12.0 of the maven-compiler-plugin.
+As you can see, it shows that with version 3.14.0 there is a Maven 3 
compatible update, while the versions 4.0.0-beta-1 and 4.0.0-beta-2 require 
Maven 4 versions.
+
+```
+[INFO] The following plugin updates are available:
+[INFO]   maven-compiler-plugin ............................ 3.12.0 -> 3.14.0
+[INFO]
+[INFO] All plugins have a version specified.
+[INFO]
+[INFO] Project requires minimum Maven version for build of: 3.9
+[INFO] Plugins require minimum Maven version of: 3.6.3
+[INFO]
+[INFO] No plugins require a newer version of Maven than specified by the pom.
+[INFO]
+[INFO] Require Maven 4.0.0-beta-3 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-1
+[INFO]
+[INFO] Require Maven 4.0.0-rc-2 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-2
+```
+
+## Required changes
+
+You need to do the following steps to be able to use Maven 4.
+
+### Upgrade build environment to support Java 17
+
+Maven 4 requires Java 17 to be run.
+This means the build environment (locally but also your CI environment) needs 
to provide a JDK that supports Java 17.
+Either install one to your machine or use a container providing one.
+
+**Note**: Maven 3 can also use executed with Java 17.

Review Comment:
   ```suggestion
   **Note**: Maven 3 can also be executed with Java 17.
   ```
   



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.
+* This guide does not contain information about how to update plugins to use 
the new Maven 4 plugin API.
+  It is planed to create a separate guide for this.
+
+## Table of content
+
+<!--MACRO{toc|fromDepth=2|toDepth=4}-->
+
+## Prerequisites
+
+This guide assumes that your environment and project meets the following 
prerequisites.
+If they don't fulfill them already, please put effort into meeting them, 
before continuing with this guide.
+
+### Use latest version of Maven 3.9
+
+This guide assumes that the project to be migrated was successfully built 
using the [latest version of Maven 3](/docs/history.html).
+
+### Upgrade plugins to their latest Maven 3 version
+
+Similar to the previous prerequisite, the guides assumes that you are using 
the latest Maven 3 plugin version of all your plugins.
+
+Do not upgrade to a plugin version, which requires Maven 4!
+Be aware of this, if you use tools that can automate updates.
+
+You can use the [versions-maven-plugin's `display-plugin-updates` 
goal][versionpluginupdate], to see which are the latest available versions of 
the plugins you use.
+
+The following example shows the output of the Versions Maven Plugin in a 
project using the outdated version 3.12.0 of the maven-compiler-plugin.
+As you can see, it shows that with version 3.14.0 there is a Maven 3 
compatible update, while the versions 4.0.0-beta-1 and 4.0.0-beta-2 require 
Maven 4 versions.
+
+```
+[INFO] The following plugin updates are available:
+[INFO]   maven-compiler-plugin ............................ 3.12.0 -> 3.14.0
+[INFO]
+[INFO] All plugins have a version specified.
+[INFO]
+[INFO] Project requires minimum Maven version for build of: 3.9
+[INFO] Plugins require minimum Maven version of: 3.6.3
+[INFO]
+[INFO] No plugins require a newer version of Maven than specified by the pom.
+[INFO]
+[INFO] Require Maven 4.0.0-beta-3 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-1
+[INFO]
+[INFO] Require Maven 4.0.0-rc-2 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-2
+```
+
+## Required changes
+
+You need to do the following steps to be able to use Maven 4.
+
+### Upgrade build environment to support Java 17
+
+Maven 4 requires Java 17 to be run.
+This means the build environment (locally but also your CI environment) needs 
to provide a JDK that supports Java 17.
+Either install one to your machine or use a container providing one.
+
+**Note**: Maven 3 can also use executed with Java 17.
+So you should prepare your build environment as soon as possible to have a 
solid, project independent base for further migration.
+
+### Install and use Maven 4
+
+After you have upgraded your build environment to support Java 17, you also 
need to provide Maven 4.
+See the information [where to download](/download.cgi) and [how to 
install](/install.html) Maven 4 for further information.
+
+Places where you might have to configure Maven 4 usage aside installation:
+* [Maven Wrapper](/wrapper/index.html)'s `maven-wrapper.properties` file.
+* [Required Maven version](/enforcer/enforcer-rules/requireMavenVersion.html) 
rule of the Maven enforcer plugin.
+* Your own CI/CD configuration scripts or pipelines.
+
+### Update plugins to Maven 4 version
+
+If there is a dedicated Maven 4 version for used plugins, you should update to 
such a version.
+You can use the [Versions Maven Plugin's `display-plugin-updates` 
goal][versionpluginupdate] to check for updates.
+
+**Note**: While Maven 4.0.0 aims to support all Maven 3.9 compatible plugins, 
this can not be guaranteed for custom plugins which use outdated plugin API 
methods.

Review Comment:
   ```suggestion
   **Note**: While Maven 4.0.0 aims to support all Maven 3.9 compatible 
plugins, this can not be guaranteed for plugins which use outdated plugin API 
methods.
   ```
   



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.
+* This guide does not contain information about how to update plugins to use 
the new Maven 4 plugin API.
+  It is planed to create a separate guide for this.
+
+## Table of content
+
+<!--MACRO{toc|fromDepth=2|toDepth=4}-->
+
+## Prerequisites
+
+This guide assumes that your environment and project meets the following 
prerequisites.
+If they don't fulfill them already, please put effort into meeting them, 
before continuing with this guide.
+
+### Use latest version of Maven 3.9
+
+This guide assumes that the project to be migrated was successfully built 
using the [latest version of Maven 3](/docs/history.html).
+
+### Upgrade plugins to their latest Maven 3 version
+
+Similar to the previous prerequisite, the guides assumes that you are using 
the latest Maven 3 plugin version of all your plugins.
+
+Do not upgrade to a plugin version, which requires Maven 4!
+Be aware of this, if you use tools that can automate updates.
+
+You can use the [versions-maven-plugin's `display-plugin-updates` 
goal][versionpluginupdate], to see which are the latest available versions of 
the plugins you use.

Review Comment:
   ```suggestion
   You can use the [versions-maven-plugin's `display-plugin-updates` 
goal][versionpluginupdate] to see which are the latest available versions of 
the plugins you use.
   ```
   



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.
+* This guide does not contain information about how to update plugins to use 
the new Maven 4 plugin API.
+  It is planed to create a separate guide for this.
+
+## Table of content
+
+<!--MACRO{toc|fromDepth=2|toDepth=4}-->
+
+## Prerequisites
+
+This guide assumes that your environment and project meets the following 
prerequisites.
+If they don't fulfill them already, please put effort into meeting them, 
before continuing with this guide.
+
+### Use latest version of Maven 3.9
+
+This guide assumes that the project to be migrated was successfully built 
using the [latest version of Maven 3](/docs/history.html).
+
+### Upgrade plugins to their latest Maven 3 version
+
+Similar to the previous prerequisite, the guides assumes that you are using 
the latest Maven 3 plugin version of all your plugins.
+
+Do not upgrade to a plugin version, which requires Maven 4!
+Be aware of this, if you use tools that can automate updates.
+
+You can use the [versions-maven-plugin's `display-plugin-updates` 
goal][versionpluginupdate], to see which are the latest available versions of 
the plugins you use.
+
+The following example shows the output of the Versions Maven Plugin in a 
project using the outdated version 3.12.0 of the maven-compiler-plugin.

Review Comment:
   ```suggestion
   The following example shows the output of the Versions Maven Plugin in a 
project using the outdated version 3.12.0 of the Maven Compiler Plugin.
   ```
   



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.
+* This guide does not contain information about how to update plugins to use 
the new Maven 4 plugin API.
+  It is planed to create a separate guide for this.
+
+## Table of content
+
+<!--MACRO{toc|fromDepth=2|toDepth=4}-->
+
+## Prerequisites
+
+This guide assumes that your environment and project meets the following 
prerequisites.
+If they don't fulfill them already, please put effort into meeting them, 
before continuing with this guide.
+
+### Use latest version of Maven 3.9
+
+This guide assumes that the project to be migrated was successfully built 
using the [latest version of Maven 3](/docs/history.html).
+
+### Upgrade plugins to their latest Maven 3 version
+
+Similar to the previous prerequisite, the guides assumes that you are using 
the latest Maven 3 plugin version of all your plugins.
+
+Do not upgrade to a plugin version, which requires Maven 4!
+Be aware of this, if you use tools that can automate updates.
+
+You can use the [versions-maven-plugin's `display-plugin-updates` 
goal][versionpluginupdate], to see which are the latest available versions of 
the plugins you use.
+
+The following example shows the output of the Versions Maven Plugin in a 
project using the outdated version 3.12.0 of the maven-compiler-plugin.
+As you can see, it shows that with version 3.14.0 there is a Maven 3 
compatible update, while the versions 4.0.0-beta-1 and 4.0.0-beta-2 require 
Maven 4 versions.
+
+```
+[INFO] The following plugin updates are available:
+[INFO]   maven-compiler-plugin ............................ 3.12.0 -> 3.14.0
+[INFO]
+[INFO] All plugins have a version specified.
+[INFO]
+[INFO] Project requires minimum Maven version for build of: 3.9
+[INFO] Plugins require minimum Maven version of: 3.6.3
+[INFO]
+[INFO] No plugins require a newer version of Maven than specified by the pom.
+[INFO]
+[INFO] Require Maven 4.0.0-beta-3 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-1
+[INFO]
+[INFO] Require Maven 4.0.0-rc-2 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-2
+```
+
+## Required changes
+
+You need to do the following steps to be able to use Maven 4.
+
+### Upgrade build environment to support Java 17
+
+Maven 4 requires Java 17 to be run.
+This means the build environment (locally but also your CI environment) needs 
to provide a JDK that supports Java 17.
+Either install one to your machine or use a container providing one.
+
+**Note**: Maven 3 can also use executed with Java 17.
+So you should prepare your build environment as soon as possible to have a 
solid, project independent base for further migration.
+
+### Install and use Maven 4
+
+After you have upgraded your build environment to support Java 17, you also 
need to provide Maven 4.
+See the information [where to download](/download.cgi) and [how to 
install](/install.html) Maven 4 for further information.
+
+Places where you might have to configure Maven 4 usage aside installation:
+* [Maven Wrapper](/wrapper/index.html)'s `maven-wrapper.properties` file.
+* [Required Maven version](/enforcer/enforcer-rules/requireMavenVersion.html) 
rule of the Maven enforcer plugin.
+* Your own CI/CD configuration scripts or pipelines.
+
+### Update plugins to Maven 4 version
+
+If there is a dedicated Maven 4 version for used plugins, you should update to 
such a version.
+You can use the [Versions Maven Plugin's `display-plugin-updates` 
goal][versionpluginupdate] to check for updates.
+
+**Note**: While Maven 4.0.0 aims to support all Maven 3.9 compatible plugins, 
this can not be guaranteed for custom plugins which use outdated plugin API 
methods.
+
+## Troubleshooting and required changes if situation applies
+
+The following changes are in general not required by all projects, but might 
apply to yours.
+
+### Fix plugin misconfigurations
+
+There are several misconfigurations in the project's POM declaration that 
result in warnings when using Maven 3.9.
+While your build should not throw any warnings at all, the following ones 
needs to be fixed as they will fail the build in Maven 4.
+
+**Notes**:
+* The [plugin configuration 
guide](/guides/mini/guide-configuring-plugins.html) contains general 
information, how plugins are correctly declared and configured.
+* For analysing wrong build behavior, it might help to use the new 
`--fail-on-severity` parameter, paired with `WARN` as an argument, to fail your 
build when a warning occur.
+
+#### Duplicate plugin declaration
+
+A plugin must only be declared once.
+Defining it multiple times, results the following log message.
+
+> 'build.plugins.plugin.(groupId:artifactId)' must be unique but found 
duplicate declaration of plugin [plugin-name] ...
+
+To fix this, remove the duplicated configuration.
+
+### Replace removed directory properties
+
+Maven 4 introduces new public properties dedicated to point to the root and 
top directory of (multi-subproject) project.
+You can now use `${project.rootDirectory}`, `${session.topDirectory}`, 
`${session.rootDirectory}` when declaring paths.
+See the [Maven Model Builder interpolation 
reference][modelbuilderinterpolation] for more details.
+
+At the same time, several (especially internal) properties are deprecated or 
removed.
+This includes the following properties:
+* `executionRootDirectory`
+* `multiModuleProjectDirector`
+
+### Replace conceptional `pre-` and `post-` lifecycle phases
+
+In Maven 3 some lifecycle phases also had conceptional `pre-` and `post-` 
phases, but they were not available for all phases.
+In Maven 4 those phases are removed in favor of new `before:` and `after:` 
phases, available for all lifecycle phases.
+
+## Optional changes and features
+
+### Changed default values
+
+#### Install / deploy at end of build
+
+Both, the maven-install-plugin and the maven-deploy-plugin, have changed 
default values for their behavior, about when to install respectively deploy.
+The default values for `installAtEnd` and `deployAtEnd` are set to `true` in 
Maven 4.
+They now reflect the desired behavior for the majority of the Maven builds.
+If you manually set these values to `true` before, you can remove the explicit 
declaration and inherit the same behavior from the new default values now.
+
+If your build relies on the old default value (`false`), you have to add it to 
your plugin configuration now. But in most cases, a build that requires the 
values to be `false` means that these settings hide a configuration error.
+We suggest to analyse the build configuration after migration.
+
+### Use POM model version 4.1.0
+
+Using POM model version 4.1.0 is not required with Maven 4.0.0.
+It is only required, for using new POM features like `root`-attribute, BOM 
packaging types, optional profiles and others.
+
+Model version 4.1.0 (or higher) will be required in future versions of Maven.
+It's suggested to migrate your project to Maven 4 without any POM changes that 
require model version 4.1.0 first.
+After you have successfully done this, include wanted features step by step.
+
+#### Define project's root directory
+
+It is highly recommended to define the project's root directory.
+While the definition is not enforced with Maven 4.0.0, it might be in the 
future.
+Some new Maven 4 features, for example the `${project.rootDirectory}`property, 
do require it.
+
+When the root directory is not defined, the following warning is displayed:
+
+> [WARNING] Unable to find the root directory. Create a .mvn directory in the 
root directory or add the root="true" attribute on the root project's model to 
identify it.
+
+As written in the warning there are two ways to define the root directory:
+
+1. Create a `.mvn` directory in the root directory.
+   The directory can be empty, however you can consider to place 
[configuration files](https://maven.apache.org/configure.html) in it.

Review Comment:
   Note that in some version control systems, an empty directory is not checked 
in to version control. Therefore, placing an empty file inside (or a Maven 
configuration file) works around this.



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.
+* This guide does not contain information about how to update plugins to use 
the new Maven 4 plugin API.
+  It is planed to create a separate guide for this.
+
+## Table of content
+
+<!--MACRO{toc|fromDepth=2|toDepth=4}-->
+
+## Prerequisites
+
+This guide assumes that your environment and project meets the following 
prerequisites.
+If they don't fulfill them already, please put effort into meeting them, 
before continuing with this guide.
+
+### Use latest version of Maven 3.9
+
+This guide assumes that the project to be migrated was successfully built 
using the [latest version of Maven 3](/docs/history.html).
+
+### Upgrade plugins to their latest Maven 3 version
+
+Similar to the previous prerequisite, the guides assumes that you are using 
the latest Maven 3 plugin version of all your plugins.
+
+Do not upgrade to a plugin version, which requires Maven 4!
+Be aware of this, if you use tools that can automate updates.
+
+You can use the [versions-maven-plugin's `display-plugin-updates` 
goal][versionpluginupdate], to see which are the latest available versions of 
the plugins you use.
+
+The following example shows the output of the Versions Maven Plugin in a 
project using the outdated version 3.12.0 of the maven-compiler-plugin.
+As you can see, it shows that with version 3.14.0 there is a Maven 3 
compatible update, while the versions 4.0.0-beta-1 and 4.0.0-beta-2 require 
Maven 4 versions.
+
+```
+[INFO] The following plugin updates are available:
+[INFO]   maven-compiler-plugin ............................ 3.12.0 -> 3.14.0
+[INFO]
+[INFO] All plugins have a version specified.
+[INFO]
+[INFO] Project requires minimum Maven version for build of: 3.9
+[INFO] Plugins require minimum Maven version of: 3.6.3
+[INFO]
+[INFO] No plugins require a newer version of Maven than specified by the pom.
+[INFO]
+[INFO] Require Maven 4.0.0-beta-3 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-1
+[INFO]
+[INFO] Require Maven 4.0.0-rc-2 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-2
+```
+
+## Required changes
+
+You need to do the following steps to be able to use Maven 4.
+
+### Upgrade build environment to support Java 17
+
+Maven 4 requires Java 17 to be run.
+This means the build environment (locally but also your CI environment) needs 
to provide a JDK that supports Java 17.
+Either install one to your machine or use a container providing one.
+
+**Note**: Maven 3 can also use executed with Java 17.
+So you should prepare your build environment as soon as possible to have a 
solid, project independent base for further migration.
+
+### Install and use Maven 4
+
+After you have upgraded your build environment to support Java 17, you also 
need to provide Maven 4.
+See the information [where to download](/download.cgi) and [how to 
install](/install.html) Maven 4 for further information.
+
+Places where you might have to configure Maven 4 usage aside installation:
+* [Maven Wrapper](/wrapper/index.html)'s `maven-wrapper.properties` file.
+* [Required Maven version](/enforcer/enforcer-rules/requireMavenVersion.html) 
rule of the Maven enforcer plugin.
+* Your own CI/CD configuration scripts or pipelines.
+
+### Update plugins to Maven 4 version
+
+If there is a dedicated Maven 4 version for used plugins, you should update to 
such a version.
+You can use the [Versions Maven Plugin's `display-plugin-updates` 
goal][versionpluginupdate] to check for updates.
+
+**Note**: While Maven 4.0.0 aims to support all Maven 3.9 compatible plugins, 
this can not be guaranteed for custom plugins which use outdated plugin API 
methods.
+
+## Troubleshooting and required changes if situation applies
+
+The following changes are in general not required by all projects, but might 
apply to yours.
+
+### Fix plugin misconfigurations
+
+There are several misconfigurations in the project's POM declaration that 
result in warnings when using Maven 3.9.
+While your build should not throw any warnings at all, the following ones 
needs to be fixed as they will fail the build in Maven 4.
+
+**Notes**:
+* The [plugin configuration 
guide](/guides/mini/guide-configuring-plugins.html) contains general 
information, how plugins are correctly declared and configured.
+* For analysing wrong build behavior, it might help to use the new 
`--fail-on-severity` parameter, paired with `WARN` as an argument, to fail your 
build when a warning occur.
+
+#### Duplicate plugin declaration
+
+A plugin must only be declared once.
+Defining it multiple times, results the following log message.

Review Comment:
   ```suggestion
   Defining it multiple times results the following log message.
   ```



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.
+* This guide does not contain information about how to update plugins to use 
the new Maven 4 plugin API.
+  It is planed to create a separate guide for this.
+
+## Table of content
+
+<!--MACRO{toc|fromDepth=2|toDepth=4}-->
+
+## Prerequisites
+
+This guide assumes that your environment and project meets the following 
prerequisites.
+If they don't fulfill them already, please put effort into meeting them, 
before continuing with this guide.
+
+### Use latest version of Maven 3.9
+
+This guide assumes that the project to be migrated was successfully built 
using the [latest version of Maven 3](/docs/history.html).
+
+### Upgrade plugins to their latest Maven 3 version
+
+Similar to the previous prerequisite, the guides assumes that you are using 
the latest Maven 3 plugin version of all your plugins.
+
+Do not upgrade to a plugin version, which requires Maven 4!
+Be aware of this, if you use tools that can automate updates.
+
+You can use the [versions-maven-plugin's `display-plugin-updates` 
goal][versionpluginupdate], to see which are the latest available versions of 
the plugins you use.
+
+The following example shows the output of the Versions Maven Plugin in a 
project using the outdated version 3.12.0 of the maven-compiler-plugin.
+As you can see, it shows that with version 3.14.0 there is a Maven 3 
compatible update, while the versions 4.0.0-beta-1 and 4.0.0-beta-2 require 
Maven 4 versions.
+
+```
+[INFO] The following plugin updates are available:
+[INFO]   maven-compiler-plugin ............................ 3.12.0 -> 3.14.0
+[INFO]
+[INFO] All plugins have a version specified.
+[INFO]
+[INFO] Project requires minimum Maven version for build of: 3.9
+[INFO] Plugins require minimum Maven version of: 3.6.3
+[INFO]
+[INFO] No plugins require a newer version of Maven than specified by the pom.
+[INFO]
+[INFO] Require Maven 4.0.0-beta-3 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-1
+[INFO]
+[INFO] Require Maven 4.0.0-rc-2 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-2
+```
+
+## Required changes
+
+You need to do the following steps to be able to use Maven 4.
+
+### Upgrade build environment to support Java 17
+
+Maven 4 requires Java 17 to be run.
+This means the build environment (locally but also your CI environment) needs 
to provide a JDK that supports Java 17.
+Either install one to your machine or use a container providing one.
+
+**Note**: Maven 3 can also use executed with Java 17.
+So you should prepare your build environment as soon as possible to have a 
solid, project independent base for further migration.
+
+### Install and use Maven 4
+
+After you have upgraded your build environment to support Java 17, you also 
need to provide Maven 4.
+See the information [where to download](/download.cgi) and [how to 
install](/install.html) Maven 4 for further information.
+
+Places where you might have to configure Maven 4 usage aside installation:
+* [Maven Wrapper](/wrapper/index.html)'s `maven-wrapper.properties` file.
+* [Required Maven version](/enforcer/enforcer-rules/requireMavenVersion.html) 
rule of the Maven enforcer plugin.
+* Your own CI/CD configuration scripts or pipelines.
+
+### Update plugins to Maven 4 version
+
+If there is a dedicated Maven 4 version for used plugins, you should update to 
such a version.
+You can use the [Versions Maven Plugin's `display-plugin-updates` 
goal][versionpluginupdate] to check for updates.
+
+**Note**: While Maven 4.0.0 aims to support all Maven 3.9 compatible plugins, 
this can not be guaranteed for custom plugins which use outdated plugin API 
methods.
+
+## Troubleshooting and required changes if situation applies
+
+The following changes are in general not required by all projects, but might 
apply to yours.
+
+### Fix plugin misconfigurations
+
+There are several misconfigurations in the project's POM declaration that 
result in warnings when using Maven 3.9.
+While your build should not throw any warnings at all, the following ones 
needs to be fixed as they will fail the build in Maven 4.
+
+**Notes**:
+* The [plugin configuration 
guide](/guides/mini/guide-configuring-plugins.html) contains general 
information, how plugins are correctly declared and configured.
+* For analysing wrong build behavior, it might help to use the new 
`--fail-on-severity` parameter, paired with `WARN` as an argument, to fail your 
build when a warning occur.
+
+#### Duplicate plugin declaration
+
+A plugin must only be declared once.
+Defining it multiple times, results the following log message.
+
+> 'build.plugins.plugin.(groupId:artifactId)' must be unique but found 
duplicate declaration of plugin [plugin-name] ...
+
+To fix this, remove the duplicated configuration.
+
+### Replace removed directory properties
+
+Maven 4 introduces new public properties dedicated to point to the root and 
top directory of (multi-subproject) project.
+You can now use `${project.rootDirectory}`, `${session.topDirectory}`, 
`${session.rootDirectory}` when declaring paths.
+See the [Maven Model Builder interpolation 
reference][modelbuilderinterpolation] for more details.
+
+At the same time, several (especially internal) properties are deprecated or 
removed.
+This includes the following properties:
+* `executionRootDirectory`
+* `multiModuleProjectDirector`
+
+### Replace conceptional `pre-` and `post-` lifecycle phases
+
+In Maven 3 some lifecycle phases also had conceptional `pre-` and `post-` 
phases, but they were not available for all phases.
+In Maven 4 those phases are removed in favor of new `before:` and `after:` 
phases, available for all lifecycle phases.

Review Comment:
   To make it more actionable, maybe we should add "update your plugin 
executions that bind to a `pre-` or `-post` phase with the corresponding 
`before:` or `after:` phases".



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.
+* This guide does not contain information about how to update plugins to use 
the new Maven 4 plugin API.
+  It is planed to create a separate guide for this.
+
+## Table of content
+
+<!--MACRO{toc|fromDepth=2|toDepth=4}-->
+
+## Prerequisites
+
+This guide assumes that your environment and project meets the following 
prerequisites.
+If they don't fulfill them already, please put effort into meeting them, 
before continuing with this guide.
+
+### Use latest version of Maven 3.9
+
+This guide assumes that the project to be migrated was successfully built 
using the [latest version of Maven 3](/docs/history.html).
+
+### Upgrade plugins to their latest Maven 3 version
+
+Similar to the previous prerequisite, the guides assumes that you are using 
the latest Maven 3 plugin version of all your plugins.
+
+Do not upgrade to a plugin version, which requires Maven 4!
+Be aware of this, if you use tools that can automate updates.
+
+You can use the [versions-maven-plugin's `display-plugin-updates` 
goal][versionpluginupdate], to see which are the latest available versions of 
the plugins you use.
+
+The following example shows the output of the Versions Maven Plugin in a 
project using the outdated version 3.12.0 of the maven-compiler-plugin.
+As you can see, it shows that with version 3.14.0 there is a Maven 3 
compatible update, while the versions 4.0.0-beta-1 and 4.0.0-beta-2 require 
Maven 4 versions.
+
+```
+[INFO] The following plugin updates are available:
+[INFO]   maven-compiler-plugin ............................ 3.12.0 -> 3.14.0
+[INFO]
+[INFO] All plugins have a version specified.
+[INFO]
+[INFO] Project requires minimum Maven version for build of: 3.9
+[INFO] Plugins require minimum Maven version of: 3.6.3
+[INFO]
+[INFO] No plugins require a newer version of Maven than specified by the pom.
+[INFO]
+[INFO] Require Maven 4.0.0-beta-3 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-1
+[INFO]
+[INFO] Require Maven 4.0.0-rc-2 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-2
+```
+
+## Required changes
+
+You need to do the following steps to be able to use Maven 4.
+
+### Upgrade build environment to support Java 17
+
+Maven 4 requires Java 17 to be run.
+This means the build environment (locally but also your CI environment) needs 
to provide a JDK that supports Java 17.
+Either install one to your machine or use a container providing one.
+
+**Note**: Maven 3 can also use executed with Java 17.
+So you should prepare your build environment as soon as possible to have a 
solid, project independent base for further migration.
+
+### Install and use Maven 4
+
+After you have upgraded your build environment to support Java 17, you also 
need to provide Maven 4.
+See the information [where to download](/download.cgi) and [how to 
install](/install.html) Maven 4 for further information.
+
+Places where you might have to configure Maven 4 usage aside installation:
+* [Maven Wrapper](/wrapper/index.html)'s `maven-wrapper.properties` file.
+* [Required Maven version](/enforcer/enforcer-rules/requireMavenVersion.html) 
rule of the Maven enforcer plugin.
+* Your own CI/CD configuration scripts or pipelines.
+
+### Update plugins to Maven 4 version
+
+If there is a dedicated Maven 4 version for used plugins, you should update to 
such a version.
+You can use the [Versions Maven Plugin's `display-plugin-updates` 
goal][versionpluginupdate] to check for updates.
+
+**Note**: While Maven 4.0.0 aims to support all Maven 3.9 compatible plugins, 
this can not be guaranteed for custom plugins which use outdated plugin API 
methods.
+
+## Troubleshooting and required changes if situation applies
+
+The following changes are in general not required by all projects, but might 
apply to yours.
+
+### Fix plugin misconfigurations
+
+There are several misconfigurations in the project's POM declaration that 
result in warnings when using Maven 3.9.
+While your build should not throw any warnings at all, the following ones 
needs to be fixed as they will fail the build in Maven 4.
+
+**Notes**:
+* The [plugin configuration 
guide](/guides/mini/guide-configuring-plugins.html) contains general 
information, how plugins are correctly declared and configured.
+* For analysing wrong build behavior, it might help to use the new 
`--fail-on-severity` parameter, paired with `WARN` as an argument, to fail your 
build when a warning occur.
+
+#### Duplicate plugin declaration
+
+A plugin must only be declared once.
+Defining it multiple times, results the following log message.
+
+> 'build.plugins.plugin.(groupId:artifactId)' must be unique but found 
duplicate declaration of plugin [plugin-name] ...
+
+To fix this, remove the duplicated configuration.
+
+### Replace removed directory properties
+
+Maven 4 introduces new public properties dedicated to point to the root and 
top directory of (multi-subproject) project.
+You can now use `${project.rootDirectory}`, `${session.topDirectory}`, 
`${session.rootDirectory}` when declaring paths.
+See the [Maven Model Builder interpolation 
reference][modelbuilderinterpolation] for more details.
+
+At the same time, several (especially internal) properties are deprecated or 
removed.
+This includes the following properties:
+* `executionRootDirectory`
+* `multiModuleProjectDirector`
+
+### Replace conceptional `pre-` and `post-` lifecycle phases
+
+In Maven 3 some lifecycle phases also had conceptional `pre-` and `post-` 
phases, but they were not available for all phases.
+In Maven 4 those phases are removed in favor of new `before:` and `after:` 
phases, available for all lifecycle phases.
+
+## Optional changes and features
+
+### Changed default values
+
+#### Install / deploy at end of build
+
+Both, the maven-install-plugin and the maven-deploy-plugin, have changed 
default values for their behavior, about when to install respectively deploy.

Review Comment:
   ```suggestion
   Both the Maven Install Plugin and the Maven Deploy Plugin have changed 
default values for their behavior, about when to install respectively deploy.
   ```



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.
+* This guide does not contain information about how to update plugins to use 
the new Maven 4 plugin API.
+  It is planed to create a separate guide for this.
+
+## Table of content
+
+<!--MACRO{toc|fromDepth=2|toDepth=4}-->
+
+## Prerequisites
+
+This guide assumes that your environment and project meets the following 
prerequisites.
+If they don't fulfill them already, please put effort into meeting them, 
before continuing with this guide.
+
+### Use latest version of Maven 3.9
+
+This guide assumes that the project to be migrated was successfully built 
using the [latest version of Maven 3](/docs/history.html).
+
+### Upgrade plugins to their latest Maven 3 version
+
+Similar to the previous prerequisite, the guides assumes that you are using 
the latest Maven 3 plugin version of all your plugins.
+
+Do not upgrade to a plugin version, which requires Maven 4!
+Be aware of this, if you use tools that can automate updates.
+
+You can use the [versions-maven-plugin's `display-plugin-updates` 
goal][versionpluginupdate], to see which are the latest available versions of 
the plugins you use.
+
+The following example shows the output of the Versions Maven Plugin in a 
project using the outdated version 3.12.0 of the maven-compiler-plugin.
+As you can see, it shows that with version 3.14.0 there is a Maven 3 
compatible update, while the versions 4.0.0-beta-1 and 4.0.0-beta-2 require 
Maven 4 versions.
+
+```
+[INFO] The following plugin updates are available:
+[INFO]   maven-compiler-plugin ............................ 3.12.0 -> 3.14.0
+[INFO]
+[INFO] All plugins have a version specified.
+[INFO]
+[INFO] Project requires minimum Maven version for build of: 3.9
+[INFO] Plugins require minimum Maven version of: 3.6.3
+[INFO]
+[INFO] No plugins require a newer version of Maven than specified by the pom.
+[INFO]
+[INFO] Require Maven 4.0.0-beta-3 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-1
+[INFO]
+[INFO] Require Maven 4.0.0-rc-2 to use the following plugin updates:
+[INFO]   maven-compiler-plugin ...................... 3.12.0 -> 4.0.0-beta-2
+```
+
+## Required changes
+
+You need to do the following steps to be able to use Maven 4.
+
+### Upgrade build environment to support Java 17
+
+Maven 4 requires Java 17 to be run.
+This means the build environment (locally but also your CI environment) needs 
to provide a JDK that supports Java 17.
+Either install one to your machine or use a container providing one.
+
+**Note**: Maven 3 can also use executed with Java 17.
+So you should prepare your build environment as soon as possible to have a 
solid, project independent base for further migration.
+
+### Install and use Maven 4
+
+After you have upgraded your build environment to support Java 17, you also 
need to provide Maven 4.
+See the information [where to download](/download.cgi) and [how to 
install](/install.html) Maven 4 for further information.
+
+Places where you might have to configure Maven 4 usage aside installation:
+* [Maven Wrapper](/wrapper/index.html)'s `maven-wrapper.properties` file.
+* [Required Maven version](/enforcer/enforcer-rules/requireMavenVersion.html) 
rule of the Maven enforcer plugin.
+* Your own CI/CD configuration scripts or pipelines.
+
+### Update plugins to Maven 4 version
+
+If there is a dedicated Maven 4 version for used plugins, you should update to 
such a version.
+You can use the [Versions Maven Plugin's `display-plugin-updates` 
goal][versionpluginupdate] to check for updates.
+
+**Note**: While Maven 4.0.0 aims to support all Maven 3.9 compatible plugins, 
this can not be guaranteed for custom plugins which use outdated plugin API 
methods.

Review Comment:
   The original text might raise the question, what is a "custom" plugin and 
what is not. The statement equally applies to each plugin, so I'd suggest to 
drop that single word.



##########
content/markdown/guides/mini/guide-migration-to-mvn4.md:
##########
@@ -0,0 +1,339 @@
+# Migrate to Maven 4
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Maven 4 introduces several upgrades and improvements (see ["What's new in 
Maven 4?"](/whatsnewinmaven4.html)).
+Some of them are backwards compatible or optional, but some require changes of 
your build environment or Maven project.
+This page offers help for users who want to build their projects with Maven 4.
+
+In short, the general suggestion for the migration is to do it in three steps:
+
+1. Meet the prerequisites
+2. Use Maven 4 for your build and fix build errors
+3. Introduces optional Maven 4 features
+
+If you run into any issues, please don't hesitate to contact the [users 
mailing list](/mailing-lists.html).
+The Maven team is interested in all your migration experiences - either good 
or bad!
+
+**Notes**:
+
+* This page will constantly be updated  to contain changes, but also to 
integrate feedback of the community and their experience when upgrading to 
Maven 4.
+  This means it will still receive updates after Maven 4 was already released.
+* It is planed to provide a migration tool (see 
[MNG-8649](https://issues.apache.org/jira/projects/MNG/issues/MNG-8649)), doing 
most of the steps needed to migrate a project.

Review Comment:
   Related: do we want to provide such a tool from our side, or can we team up 
with OpenRewrite? They might already have something in the making.



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