code: public TrailingHeaders setHeader(CharSequence name, Iterable<Object> values) {
          lastHttpContent.trailingHeaders().set(name, values);
          return this;
      }
docs: Overwrites the current value, if any, of the passed trailing header to the passed values for this request.
  
  @param name Name of the header.
  @param values Values of the header.
  
  @return {@code this}.