return new ForwardingSub(sub);
              }
            });
  }

  interface Base {
    CharSequence getId();
  }

  interface Sub extends Base {
    @Override
    String getId();
  }

  private static class ForwardingSub implements Sub {
    private final Sub delegate;

    ForwardingSub(Sub delegate) {
      this.delegate = delegate;
    }

                return new ForwardingSub(sub);
              }
            });
  }

  interface Base {
    CharSequence getId();
  }

  interface Sub extends Base {
    @Override
    String getId();
  }

  private static class ForwardingSub implements Sub {
    private final Sub delegate;

    ForwardingSub(Sub delegate) {
      this.delegate = delegate;
    }