Cannot import images from non-default groups

[NicoKiaru]

Hi everybody,

In the OMERO browser, you are able to navigate throw your different groups you are part of.
But it is not possible to import in ImageJ images coming from groups that are not your default group. Only images coming from the default group (i.e. the one that is automatically displayed on the browser at opening) can be imported.

Me and @Rdornier are using this repo to collect OMERO Sessions (pixel data loading is done independently). We collect login user data like this:

https://github.com/BIOP/bigdataviewer-image-loaders/blob/ce90dde18968e6762253850e8914f08cc5d63195/src/main/java/ch/epfl/biop/bdv/img/omero/command/OmeroConnectCommand.java#L78-L82

However, we noticed that some use cases are not covered by the OMERO service, which is related to group policies. For instance, if I belong to two groups in OMERO, the security context will be initialized with my default assigned group. Meaning that if I want to access the data from my other group, it will fail because the SecurityContext is not correct. Similarly, if I am an admin and should have access to all data, I won't be able to do it, again because of my inability to change the security context, or to create a new OMERO session with a different group.

What this mean is that the 'key' to identify an OMEROSession is not the server url only. It should be the server url AND the groupId.

I do not have a clear way forward, but I can see how the current 'caching' mechanism fails:

imagej-omero/src/main/java/net/imagej/omero/DefaultOMEROService.java

Line 127 in e2e675e

OMEROSession session = sessions.get(server);

The groupId should be somehow included to identify a session:

OMEROSession session = sessions.get(server, groupId);

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We had the same issue with QuPath (BIOP/qupath-extension-biop-omero#7)

(Could be related to #112)