on_string for collections selected in `multiple=true` inputs

[bernt-matthias]

If a collection is chosen in a multiple=true input field the on_string for generated data sets is different to the case if input is a collection. Reminds me on #7392

I think it should be tool name on collection xyz in both cases. instead of ... on data a and data b...

[bernt-matthias]

At least documented/discussed now in the docs now: galaxyproject/planemo#930

[mvdbeek]

This is fixable (_get_on_text in

galaxy/lib/galaxy/tools/actions/__init__.py

Line 292 in 0b8dec5

on_text = self._get_on_text(inp_data)

would just also need to look at inp_dataset_collection), but I'm hoping we can get rid of the reference to hids (=data N ) altogether. If no explicit name is set we could just compute that string on the fly since we know the input datasets and we know the tool that was used to produce the dataset. If we did that the references would remain intact even if copied to a different history.

[bernt-matthias]

This would be great.