public LockRequestBuilder setUser(String user) {
    if (user == null) user = "unknown";
    req.setUser(user);
    userSet = true;
    return this;
  }
Set the transaction id.
@param txnid transaction id
@return reference to this builder
standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/LockRequestBuilder.java