code: public boolean isEqualMappedBy(Function<? super E, ?> expectedMapper, Function<? super A, ?> actualMapper) {
  		return isEqualBasedOn((expected, actual) -> {
  			return Objects.equals(expectedMapper.apply(expected), actualMapper.apply(actual));
  		});
  	}
docs: Returns true if the two trees are equal, by calling {@link Objects#equals(Object, Object)} on the results of both mappers.