Dear Igniters! I would like to propose a discussion about defining a policy regarding where and how to use @Nullable/@NotNull annotations. These annotations are used in conjunction with a static analysis engine (e.g. built in IDEA) and are useful for avoiding null dereferencing and specifying method contracts.
I can see the following possible options: 1. *Use both @Nullable and @NotNull annotations everywhere* (i.e. method parameters and return types, class fields). Pros: the most robust and expressive variant; easy to agree on and specify. Cons: very verbose; may lead to code cluttering; 2. *Use only @Nullable *for specifying method parameters that accept null or class fields that can be null, treating @NotNull as an implicit default. Pros: correlates with the default IDEA settings (with all corresponding inspections enabled); not as verbose as option 1, since nullable parameters are quite rare. Cons: less sound and complete, especially when working with third-party libraries that are not annotated, since we cannot apply the implicit @NotNull there; 3. *Use only @NotNull *and treat @Nullable as an implicit default. Pros: less verbose than option 1, better correlates with Java language semantics (since all Java references are nullable). Cons: more verbose than option 2; may be impossible to properly set up the analysis engine or may require switching to a different annotation provider that supports jsr-305 @ParametersAreNullableByDefault; 4. *Do not use @Nullable nor @NotNull*. The most radical option in case we will not be able to agree on any of the above three. No annotations - no need for the discussion. What do you think? Are there any other options out there? I would like to collect as many options as possible and organize a vote some time later. -- With regards, Aleksandr Polovtcev
