code: public static Class<?>[] toClassArray(Collection<Class<?>> collection) {
  		if (collection == null) {
  			return null;
  		}
  		return collection.toArray(new Class<?>[collection.size()]);
  	}
docs: Copy the given Collection into a Class array.
  The Collection must contain Class elements only.
  @param collection the Collection to copy
  @return the Class array ({@code null} if the passed-in
  Collection was {@code null})