code: public void removeDeferredTrailer(String hdr) {
          if (tc.isDebugEnabled()) {
              Tr.debug(tc, "removeDeferredTrailer(String): " + hdr);
          }
          if (null == hdr) {
              throw new IllegalArgumentException("Null header name");
          }
          this.knownTGs.remove(findKey(hdr));
      }
docs: Remove a deferred trailer from the current list of trailers to generate
  when serializing this object.
  
  The user is responsible for maintaining consistency between the trailer
  header field at the head of the HTTP request/response with the deferred
  trailer list. For instance after removeDeferredTrailer("test1"), is
  called the trailer header field should not contain "test1".
  
  @param hdr
  the trailer name to remove (i.e. 'Date').
  @throws IllegalArgumentException
  if hdr is NULL.