import java.util.Set;
import java.util.SortedSet;

/**
 * Optional features of classes derived from {@code Collection}.
 *
 * @author George van den Driessche
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible
public enum CollectionFeature implements Feature<Collection> {
  /**
   * The collection must not throw {@code NullPointerException} on calls such as {@code

import java.util.Set;
import java.util.SortedSet;

/**
 * Optional features of classes derived from {@code Collection}.
 *
 * @author George van den Driessche
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible
public enum CollectionFeature implements Feature<Collection> {
  /**
   * The collection must not throw {@code NullPointerException} on calls such as {@code