framework/tests/framework/GenericTest10.java

// Test case for (a part of) Issue 142:
// https://github.com/typetools/checker-framework/issues/142
public class GenericTest10 {
  abstract static class Bijection<A, B> {
    abstract B apply(A a);

    abstract A invert(B b);

    Bijection<B, A> inverse() {
      return new Bijection<B, A>() {
        A apply(B b) {
          return Bijection.this.invert(b);
        }

        B invert(A a) {
          return Bijection.this.apply(a);
        }

        Bijection<A, B> inverse() {
          return Bijection.this;
        }
      };
    }
  }
}