@Override
 public MasterKey getNMTokenMasterKey() {
   NodeHeartbeatResponseProtoOrBuilder p = viaProto ? proto : builder;
   if (this.nmTokenMasterKey != null) {
     return this.nmTokenMasterKey;
   }
   if (!p.hasNmTokenMasterKey()) {
     return null;
   }
   this.nmTokenMasterKey = convertFromProtoFormat(p.getNmTokenMasterKey());
   return this.nmTokenMasterKey;
 }