Unexpected source product box behaviour

Hi all,

Recently I have started developing an extension for SNAP in Python. It works as expected, but as soon as I want to run it again, I see the following in my extension menu:

All source product are filled with the same file from the previous time I used the extension. Normally this may be odd and not so much of a problem. However, in this case, the masks are optional and are sometimes empty. Unfortunately, it is impossible to empty it and “unselect” the file. Could you help me out and explain why everything is filled up and how to avoid it?

Many thanks!