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All rules, listed in this document, supplement or override the rules of the Google Java Style Guide.

Appendix A

1 Nullability annotation usages

1.1 Common annotating rules

Ignite 3 uses JetBrains nullability annotations. For the sake of code clarity it is prohibited to use @NotNull annotation, even if it compromises the completeness of static analysis. However, it is required to use @Nullable in the following places:

• On a function's return type, if the function can return null;
• On a function's parameter, if passing null as this parameter will not end in throwing an exception;
• On a class field, if it can be null.

1.2 Annotating arrays

There are multiple ways to annotate a Java array, which lead to different interpretation by the static analysis tool:

@Nullable Object[] x;            // x array can *contain* null values
Object @Nullable [] x;           // x itself can be null 
@Nullable Object @Nullable [] x; // x array can contain null values *and* be null itself

1.3 Intellij IDEA settings

It is recommended to enable all inspections, related to this topic. Please note, that all nested options should also be enabled:

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