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