in jdbc-grpc-client/src/main/java/org/apache/kyuubi/grpc/client/SimpleBlockingJdbcClient.java [343:350]
public DirectStatusResp setTransactionIsolation(String connectionId, int level) {
SetTransactionIsolationReq.Builder builder = SetTransactionIsolationReq.newBuilder();
SetTransactionIsolationReq req = builder
.setConnectionId(ConnectionHandle.newBuilder().setId(connectionId).build())
.setLevel(level)
.build();
return connectionBlockingStub.setTransactionIsolation(req);
}