Hamcrest Matcher transformed by function

gistfile1.java

public class TransformingMatcher<U, T> extends TypeSafeMatcher<U> {
    private final Matcher<T> base;
    private final Function<? super U, ? extends T> function;

    public TransformingMatcher(Matcher<T> base, Function<? super U, ? extends T> function) {
        this.base = base;
        this.function = function;
    }

    @Override
    public void describeTo(Description description) {
        description.appendText("transformed version of ");
        base.describeTo(description);
    }

    @Override
    protected boolean matchesSafely(U item) {
        return base.matches(function.apply(item));
    }
}