code: public static ErrorMessageFactory shouldHaveSize(Object actual, Object actualSize, Object expectedSize) {
      return new ShouldHaveSize(actual, actualSize, expectedSize);
    }
docs: Creates a new {@link ShouldHaveSize}.
  
  @param actual the <em>actual</em> value in the failed assertion.
  @param actualSize the size of {@code actual}.
  @param expectedSize the expected size.
  @return the created {@code ShouldHaveSize}.