org.springframework.lang

## 注释类型 NonNull

-     @Target(value={METHOD,PARAMETER,FIELD})
       @Retention(value=RUNTIME)
       @Documented
       @Nonnull
       @TypeQualifierNickname
      public @interface NonNull

  A common Spring annotation to declare that annotated elements cannot be `null`.

  Leverages JSR-305 meta-annotations to indicate nullability in Java to common tools with JSR-305 support and used by Kotlin to infer nullability of Spring API.

  Should be used at parameter, return value, and field level. Method overrides should repeat parent `@NonNull` annotations unless they behave differently.

  Use `@NonNullApi` (scope = parameters + return values) and/or `@NonNullFields` (scope = fields) to set the default behavior to non-nullable in order to avoid annotating your whole codebase with `@NonNull`.

  从以下版本开始:
    5.0
  作者:
    Sebastien Deleuze, Juergen Hoeller
  另请参阅:
    `NonNullApi`, `NonNullFields`, `Nullable`