docs: @SuppressWarnings({ "unchecked", "checkstyle:illegaltype" })
  	Collection<V> copyValues(Collection<V> values) {
  		final Object backEnd = DataViewDelegate.undelegate(values);
  		if (backEnd instanceof List<?>) {
  			return Lists.newArrayList(values);
  		}
  		if (backEnd instanceof TreeSet<?>) {
  			TreeSet<V> c = (TreeSet<V>) backEnd;
  			c = Sets.newTreeSet(c.comparator());
  			c.addAll(values);
  			return c;
  		}
  		if (backEnd instanceof LinkedHashSet<?>) {
  			return Sets.newLinkedHashSet(values);
  		}
  		if (backEnd instanceof Set<?>) {
  			return Sets.newHashSet(values);
  		}
  		throw new IllegalStateException("Unsupported type of the backend multimap: " + values.getClass()); //$NON-NLS-1$
  	}