code: public DistributerProtocolEnum getProtocol() {
      if (isReference()) {
        final DistributerDef refDistributer = (DistributerDef) getCheckedRef(DistributerDef.class, "DistributerDef");
        return refDistributer.getProtocol();
      }
      return this.protocol;
    }
docs: Gets protocol.
  
  @return protocol, may be null.