Why is UML Designer has a dependency to itself, when installing in Eclipse Oxygen

Question

I have problems installing UML Designer 9.0.0 in eclipse oxygen, getting error message:

Cannot complete the install because one or more required items could not be found.   Software being installed: UML Designer
9.0.0.201901300933 (org.obeonetwork.dsl.uml2.runtime.feature.feature.group
9.0.0.201901300933)   Missing requirement: UML Designer 9.0.0.201901300933 (org.obeonetwork.dsl.uml2.runtime.feature.feature.group
9.0.0.201901300933) requires 'org.obeonetwork.dsl.uml2.core.runtime.feature.feature.group 0.0.0' but it could not be found

seems that it requires itself to install, which is senseless

oxygen and sirius p2 repository are added

Answer 1

Look closely:

• org.obeonetwork.dsl.uml2.runtime.feature.feature.group requires
• org.obeonetwork.dsl.uml2.core.runtime.feature.feature.group

So the DSL UML2 Core feature is missing. I would suspect it in the UML Designer 9.0.0 or Nightly repository, but it's not there. In such a case you should ask the owner of the repository.