Most of the OMERO code is GPL, but some repos are A-GPL or LGPL while others are BSD.
However, I’m not quite sure what the license is for the Java Gateway?
If it’s GPL, that means any client developed with it should be GPL (and thus, any program accessing OMERO through it). I don’t have much of a problem with that, but if we code something with it, I’d rather put the appropriate license…
Although, if it’s not GPL, we could use a more permissive license (MPL, AFL, BSD, …).