code: @Nonnull
    public static <T extends Collection<?>> T assertDoesntContainNull(@Nonnull final T collection) {
      assertNotNull(collection);
      for (final Object obj : collection) {
        assertNotNull(obj);
      }
      return collection;
    }
docs: Assert that collection doesn't contain null value.
  
  @param <T>        type of collection to check
  @param collection a collection to be checked for null value
  @return the same input parameter if all is ok
  @throws AssertionError it will be thrown if either collection is null or it contains null
  @since 1.0