src/main/java/org/fest/assertions/Collections.java
public static @NotNull Collection<Object> notFound(@Nullable Collection<?> target, @NotNull Object... objects) {
    if (target == null) {
      return emptyList();
    }
    List<Object> notFound = newArrayList();
    for (Object o : objects) {
      if (!target.contains(o)) {
        notFound.add(o);
      }
    }
    return notFound;
  }
public static @NotNull Collection<Object> notFound(@Nullable Collection<?> target, @NotNull Object... objects) {
    if (target == null) {
      return emptyList();
    }
    List<Object> notFound = newArrayList();
    for (Object o : objects) {
      if (!target.contains(o)) {
        notFound.add(o);
      }
    }
    return notFound;
  }
Attempts to find the given objects in the given {@code Collection}, returning the ones that were not found.

@param target  the given {@code Collection}.
@param objects the elements to find in the given {@code Collection}.
@return the elements that were not found in the given {@code Collection}.