answer to http://stackoverflow.com/questions/3831004/java-generics-and-wildcards-how-to-make-this-code-compile

gistfile1.java

public class GenericsTest {

	public void doesNotCompile() {
		Container<String> container = new Container<String>();

		assertThat(container, hasSomethingWhich(is("foo")));
	}

	public static class Container<T> {

		public boolean hasSomethingMatching(Matcher<? super T> matcher) {
			T something = null; // here is some application logic
			return matcher.matches(something);
		}
	}

	public static <T> Matcher<Container<T>> hasSomethingWhich(final Matcher<? super T> matcher) {
		return new TypeSafeMatcher<Container<T>>() {

			@Override
			protected boolean matchesSafely(Container<T> container) {
				return container.hasSomethingMatching(matcher);
			}

			@Override
			public void describeTo(Description description) {
				// TODO Auto-generated method stub
			}
		};
	}
}