JOSM enhancements vs. separate plugin

[Jiri Hubacek]

Dear JOSM devs,

I would like to ask question about the JOSM enhancements. Where is the
line between functionality acceptable upstream and the feature that
should be in separate plugin?

The concrete example - I wrote some script for automatic creation of
residential area around the selected buildings. I rewrote it to Java to
be able to push it upstream but it looked too specific to be included in
"Tools" menu. So I created the plugin (mapathoner). Are there any
guidelines for these decisions?

Thanks,
jiri