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https://issues.apache.org/jira/browse/KAFKA-19213?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Chia-Ping Tsai resolved KAFKA-19213.
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Fix Version/s: 4.2.0
Resolution: Fixed
> Kafka java client ignores default properties
> --------------------------------------------
>
> Key: KAFKA-19213
> URL: https://issues.apache.org/jira/browse/KAFKA-19213
> Project: Kafka
> Issue Type: Bug
> Components: clients
> Affects Versions: 2.0.0, 3.0.0, 4.0.0
> Reporter: Pas Filip
> Assignee: Evanston Zhou
> Priority: Minor
> Fix For: 4.2.0
>
> Attachments: TestMapCreationFromPropertiesUsingDefaults.java
>
>
> Using Kafka Java client, when creating a kafka consumer/producer using a
> properties object with defaults the defaults are ignored.
> Not sure if this is an intentional design choice or not but it was a surprise
> to me.
> My expectation was if a KafkaConsumer or KafkaProducer accepts a Properties
> object it should not ignore the defaults in the Properties object.
>
> The culprit seems to be in the propsToMap in the Utils class.
> It doesn't use the propertyNames method to get all the keys known to the
> Properties object.
> {code:java}
> public static Map<String, Object> propsToMap(Properties properties) {
> Map<String, Object> map = new HashMap<>(properties.size());
> for (Map.Entry<Object, Object> entry : properties.entrySet()) {
> if (entry.getKey() instanceof String) {
> String k = (String) entry.getKey();
> map.put(k, properties.get(k));
> } else {
> throw new ConfigException(entry.getKey().toString(),
> entry.getValue(), "Key must be a string.");
> }
> }
> return map;
> }
> {code}
> I was using version 7.6.0-ccs of the kafka client, on the trunk branch the
> implementation seems different but is subject to the same issue:
> {code:java}
> /**
> * Convert a properties to map. All keys in properties must be string
> type. Otherwise, a ConfigException is thrown.
> * @param properties to be converted
> * @return a map including all elements in properties
> */
> public static Map<String, Object> propsToMap(Properties properties) {
> return castToStringObjectMap(properties);
> }
> /**
> * Cast a map with arbitrary type keys to be keyed on String.
> * @param inputMap A map with unknown type keys
> * @return A map with the same contents as the input map, but with String
> keys
> * @throws ConfigException if any key is not a String
> */
> public static Map<String, Object> castToStringObjectMap(Map<?, ?>
> inputMap) {
> Map<String, Object> map = new HashMap<>(inputMap.size());
> for (Map.Entry<?, ?> entry : inputMap.entrySet()) {
> if (entry.getKey() instanceof String) {
> String k = (String) entry.getKey();
> map.put(k, entry.getValue());
> } else {
> throw new ConfigException(String.valueOf(entry.getKey()),
> entry.getValue(), "Key must be a string.");
> }
> }
> return map;
> }{code}
>
> A possible suggestion for how to fix the behavior:
>
> {code:java}
> public static Map<String, Object> propsToMap(Properties properties) {
> final Enumeration<?> enumeration = properties.propertyNames();
> Map<String, Object> props = new HashMap<>();
> while (enumeration.hasMoreElements()) {
> Object key = enumeration.nextElement();
> if (key instanceof String) {
> final String keyString = (String) key;
> props.put(keyString,properties.getProperty(keyString));
> } else {
> throw new
> ConfigException(String.valueOf(key),properties.get(key), "Key must be a
> string.");
> }
> }
> return props;
> }
> {code}
> Provided a basic test case to demonstrate the issue. See file attachment.
>
>
>
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