code: protected final void removeFilter(IoFilterChain filterChain, IoFilter filter) {
          if (filterChain.contains(filter)) {
              filterChain.remove(filter);
          }
      }
docs: A utility method to remove a filter from a filter chain, without
  complaining if it is not in the chain.
  
  @param filterChain the filter chain
  @param filter      the filter to remove