DROOLS-5664 DMN editor reporting unsaved changes in DMN files after no changes

[vpellegrino]

JIRA: https://issues.redhat.com/browse/DROOLS-5664

How it works:

1. When the diagram is loaded (and the unmarshaller part already executed), this method gets called, in order to store the original diagram hash.
2. When closing the diagram session, this method checks if the session can be closed or not by comparing the original diagram hash, with the current one:
   2.1. if they are different (the method super.mayClose(getCurrentDiagramHash()) returns false), the "unsaved changes" modal is displayed.

Provided solution:
Several operations may happen before the diagram is drawn (for example element wrapping, etc.), so it is recommended to compute and store che original diagram hash after the diagram gets loaded (inspired by kie-wb-common-stunner-kogito-client)

Recorded demo:

How to retest this PR or trigger a specific build:

• Retest PR: jenkins retest this
• A full downstream build: jenkins do fdb
• A compile downstream build: jenkins do cdb
• A full production downstream build: jenkins do product fdb
• An upstream build: jenkins do upstream

[karreiro]

+1 from my side for this approach, @vpellegrino! As soon as we add an unit test, we can merge the fix :-)

[jstastny-cz]

jenkins do fdb

[jstastny-cz]

Please check build results.
Failing test:
org.kie.workbench.common.dmn.project.client.editor.DMNDiagramEditorTest.testOnDiagramLoadWhenCanvasHandlerIsNotNull

[vpellegrino]

jenkins do fdb

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities (and 0 Security Hotspots to review)
0 Code Smells

100.0% Coverage
0.0% Duplication

[karreiro]

Thank you, @vpellegrino!

[jstastny-cz]

LGTM, thanks.