code: @Nonnull
    public EChange removeRules (@Nonnull final Predicate <? super ICSSTopLevelRule> aFilter)
    {
      return EChange.valueOf (m_aRules.removeIf (aFilter));
    }
docs: Remove all rules matching the passed predicate.
  
  @param aFilter
  The predicate to apply for deletion. May not be <code>null</code>.
  @return {@link EChange#CHANGED} it at least one rule was removed,
  {@link EChange#UNCHANGED} otherwise.
  @since 5.0.0