DataFlowGraphModel.hpp , DataFlowGraphModel.cpp , UndoCommands.cpp

[qq978358810]

1:When you add a connection, you make security judgments about the data

[qq978358810]

1: Added topology connection checks to prevent cyclic connections.

2: When calling addConnection, data consistency must be verified, and it should be checked if a connection already exists (since another workflow might impact synchronization with the current workflow).

[Llcoolsouder]

@qq978358810 Can you confirm that this is different from #484 ?