code: public boolean isSet(_Fields field) {
      if (field == null) {
        throw new java.lang.IllegalArgumentException();
      }
  
      switch (field) {
      case TRACE_ID:
        return isSetTrace_id();
      case SPAN_ID:
        return isSetSpan_id();
      case PARENT_SPAN_ID:
        return isSetParent_span_id();
      case SAMPLED:
        return isSetSampled();
      case CLIENT_ID:
        return isSetClient_id();
      case FLAGS:
        return isSetFlags();
      case CONTEXTS:
        return isSetContexts();
      case DEST:
        return isSetDest();
      case DELEGATIONS:
        return isSetDelegations();
      case TRACE_ID_HIGH:
        return isSetTrace_id_high();
      }
      throw new java.lang.IllegalStateException();
    }
docs: Returns true if field corresponding to fieldID is set (has been assigned a value) and false otherwise