boolean equals(@Nullable Object obj);

    @Override
    int hashCode();

    @Override
    String toString();
  }

  private static class NoDelegateToEquals implements Equals {

    private final Equals delegate;

    NoDelegateToEquals(Equals delegate) {
      this.delegate = delegate;
    }

    @Override
    public String toString() {
      return delegate.toString();
    }
  }