3a1d8e
@@ -43,6 +43,10 @@
import org.apache.commons.collections4.iterators.PermutationIterator;
 /**
  * Provides utility methods and decorators for {@link Collection} instances.
  * <p>
+ * Various utility methods might put the input objects into a Set/Map/Bag. In case
+ * the input objects override {@link Object#equals(Object)}, it is mandatory that
+ * the general contract of the {@link Object#hashCode()} method is maintained.
+ * <p>
  * NOTE: From 4.0, method parameters will take {@link Iterable} objects when possible.
  *
  * @since 1.0
