```
@Documented
@Retention(SOURCE)
@Target({METHOD,PARAMETER,LOCAL_VARIABLE,FIELD})
public @interface Nullable
```
Denotes that a parameter, field or method return value can be null. Note: this is the default assumption for most Java APIs and the default assumption made by most static code checking tools, so usually you don't need to use this annotation; its primary use is to override a default wider annotation like NonNullByDefault.
When decorating a method call parameter, this denotes the parameter can legitimately be null and the method will gracefully deal with it. Typically used on optional parameters.
When decorating a method, this denotes the method might legitimately return null.
This is a marker annotation and it has no specific attributes.

Annotation Type Nullable