Annotation Type This

@Retention(RUNTIME)
@Target({TYPE_USE,TYPE_PARAMETER})
@PolymorphicQualifier
@TargetLocations({RECEIVER,RETURN})
public @interface This

Write @This on the return type of a method that always returns its receiver ( this). For example:

class MyBuilder {
  @This MyBuilder setName(String name) {
    this.name = name;
    return this;
  }
}

Strictly speaking, this is a polymorphic annotation, but when you write it on a return type, the Returns Receiver Checker automatically adds it to the receiver, so the above method is equivalent to:

@This MyBuilder setName(@This MyBuilder this, String name) {
  this.name = name;
  return this;
}

While it would be natural to make @This the default annotation for receivers, it leads to false positives warnings due to https://github.com/typetools/checker-framework/issues/2931, so this defaulting is currently elided.