in src/main/java/org/apache/sling/hamcrest/matchers/ResourceChildrenMatcher.java [74:78]
protected void describeMismatchSafely(Resource item, Description mismatchDescription) {
// the default would be something like ".. but item 0 was <Resource.toString()>"
// use the iterable matcher here instead
iterarableMatcher.describeMismatch(item.getChildren(), mismatchDescription);
}