in jdbc-grpc-client/src/main/java/org/apache/kyuubi/grpc/client/SimpleBlockingJdbcClient.java [294:303]
public DirectStatusResp rollback(String connectionId, String savepointName) {
Savepoint sp = Savepoint.newBuilder()
.setSavepointName(savepointName)
.build();
RollbackReq req = RollbackReq.newBuilder()
.setConnectionId(ConnectionHandle.newBuilder().setId(connectionId).build())
.setSavepoint(sp)
.build();
return connectionBlockingStub.rollback(req);
}