Fix refresh project pane handling envents bug

Signed-off-by: Nassirou NAMBIEMA nassirou.nambiena@rte-france.com

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[x ] The commit message follows our guidelines
[ ] Tests for the changes have been added (for bug fixes / features)
[ ] Docs have been added / updated (for bug fixes / features)

Does this PR already have an issue describing the problem ? If so, link to this issue using '#XXX' and skip the rest no

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...) Bug fix

What is the current behavior? (You can also link to an open issue here) when creating a new node in the tree view of the project pane, the tree item first considers the value of the node as a string, therefore when updating the projectNode contained by the item, a ClassCastException is thrown.

What is the new behavior (if this is a feature change)?

Does this PR introduce a breaking change or deprecate an API? If yes, check the following:

[ ] The Breaking Change or Deprecated label has been added
[ ] The migration guide has been updated in the github wiki (What changes might users need to make in their application due to this PR?) no breaking change

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powsybl / powsybl-gse

Fix refresh project pane handling envents bug #275