Plugin classloaders list cleared too often?

[DevCharly]

While looking for a fix for #20456, I notices something strange in PluginHandler.loadPlugins() here:
https://josm.openstreetmap.de/browser/josm/trunk/src/org/openstreetmap/josm/plugins/PluginHandler.java#L853

classLoaders is a static variable and is always cleared when PluginHandler.loadPlugins()
is invoked, which happens multiple times at startup (for very-early-plugins, early-plugins and late-plugins) and also when downloading a plugin.

This seems not right?

PluginHandler.getPluginClassLoaders() returns only the plugin classloaders of the last PluginHandler.loadPlugins() invocation.

[GerdP]

Yes, seems to be too lazy. I wonder why it is done. AFAIK we never unload plugins?

[Don-vip]

I introduced it in r14978 but I don't remember why. I don't see any reason, so it's probably better to remove the clear() call.

[Don-vip]

In 17511/josm:

fix #20458 - don't clear plugin classloaders each time we load a category of plugins