code: public <U extends T> OngoingMatchingC1<T, U, U> when(MatchesAny<U> o) {
      List<Matcher<Object>> matchers = Lists.of(ArgumentMatchers.any());
      return new OngoingMatchingC1<>(
          this,
          new DecomposableMatchBuilder1<U, U>(matchers, 0, new IdentityFieldExtractor<>()).build());
    }
docs: Specifies a wildcard match and then returns a fluent interface for specifying the action to
  take if the value matches this case.