presto-main/src/main/java/io/prestosql/execution/QueryStateMachine.java/QueryStateMachine/setStartedTransactionId
class QueryStateMachine:    public void setStartedTransactionId(TransactionId startedTransactionId)
    {
        checkArgument(!clearTransactionId.get(), "Cannot start and clear transaction ID in the same request");
        this.startedTransactionId.set(startedTransactionId);
    }