Do not allow multiple messages with the same name

[strangelookingnerd]

Describe the bug

Currently it is possible to create multiple bpmn:message (as well as escalation, errors...) with identical names but different IDs.
In the UI you can only select these message by the "global message reference" which is based on the name. For the user there is no way to distinguish them. Since I can not imagine any scenario where a user would want / need multiple messsage of the same name to be in place I'd argue that it should not be possible to create messages with identical names.

Steps to reproduce

1. Create a new message event with name MyMessage
   
2. Create another message event with the same name
   
3. End up with two messages with the same name
   

Expected behavior

It should not be possible to create multiple messages with identical names.

Environment

Camunda Modeler system information

• Version: 5.23.0
• Operating System: Windows 10 amd64
• Plugins:
• Execution Platform: BPMN - Camunda 7

Additional context

Related to #4341, #4343, #4344

[nikku]

This should be addressed via a lint rule. There is no good reason to have multiple messages with the same name. On the other hand, does it hurt?

We go by the principle of "being forgiven", but also helpful. Hence our strategy is not to prevent you from duplicating, rather we allow you to fix the issue.

[strangelookingnerd]

This should be addressed via a lint rule. There is no good reason to have multiple messages with the same name. On the other hand, does it hurt?

We go by the principle of "being forgiven", but also helpful. Hence our strategy is not to prevent you from duplicating, rather we allow you to fix the issue.

It surely does not hurt but chances are very high it was not intended by the user and thus should be warned about. Adding a lint rule sounds like a reasonable solution.

[nikku]

@strangelookingnerd Happy to take a contribution that validates this in bpmnlint.

[nikku]

This is now available and validated as a bpmnlint rule, and can be plugged-in to the modeler via the camunda-modeler-default-linter-rules plugin soonish (jonathanlukas/camunda-modeler-linter-default-rules#45).

Thanks @strangelookingnerd!