code: public HttpTrailersImpl duplicate() {
          if (null == this.myFactory) {
              if (tc.isDebugEnabled()) {
                  Tr.debug(tc, "Null factory, unable to duplicate: " + this);
              }
              return null;
          }
  
          if (tc.isDebugEnabled()) {
              Tr.debug(tc, "Duplicating the trailer headers: " + this);
          }
          computeRemainingTrailers();
          HttpTrailersImpl msg = this.myFactory.getTrailers();
          super.duplicate(msg);
          return msg;
      }
docs: Create a duplicate version of these trailer headers.
  
  @return HttpTrailersImpl