With 2.6 we change the relations possible between entities (reports, dashboard) & collections from a 1:n to a 1:1 relation. In order to guarantee a convenient migration for users we need to address this change in the migration.
- after the migration to 2.6 all collections from 2.5 still contain all the reports they contained before (report copies have to be created for every collection)
- for combined reports that references reports that where not in the same collection in 2.5 all the reports are copied to the collection that contains the combined report as well
- the rolling upgrade tests verifies that collections still contain the entities they contained before
- verify breaking schema change migration https://github.com/camunda/camunda-optimize/pull/868#discussion_r312994913
- after the migration to 2.6 all collections contain scope entries that reflect all the reports they contain