Feature Request: ErrorCollector#checkThrows overload with Matcher<Exception> parameter

[Ambeco]

Right now, ErrorCollector#checkThrows has no way to make assertions about the exception that is thrown.
This can trivially be safely added, in a backwards compatible way:

	public <E extends Throwable> void checkThrows(
			Class<E> expectedThrowable, ThrowingRunnable runnable, Matcher<E> matcher)
	{
		try {
			checkThat(assertThrows(expectedThrowable, runnable), matcher);
		} catch (AssertionError e) {
			addError(e);
		}
	}

Example Usage:

	@Test public void immutableList_is_immutable() {
		ImmutableList<String> list = list.of();

		collector.checkThrows(UnsupportedOperationException.class, () -> list.add(""), notNullValue());
	}

[marcphilipp]

@Ambeco Thanks for raising the issue! However, JUnit 4 is in "maintenance mode" which means we currently have no plans of adding new features to it, even if they're small.