docs: public final StringSubject hasMessageThat() {
      StandardSubjectBuilder check = check("getMessage()");
      if (actual() instanceof ErrorWithFacts && ((ErrorWithFacts) actual()).facts().size() > 1) {
        check =
            check.withMessage(
                "(Note from Truth: When possible, instead of asserting on the full message, assert"
                    + " about individual facts by using ExpectFailure.assertThat.)");
      }
      return check.that(actual().getMessage());
    }