More core plugin updates

[i509VCB]

No description provided.

[gabizou]

small nitpicks, but looks good.

Some of these changes, are you absolutely sure they are still necessary? I'm not sure that the ClassInheritanceMultiMap changes are still necessary, but I haven't done that investigation

[i509VCB]

I gave the class inheritance multimap another look and the condition it allows for is quite broad as one of the halves only requires just an interface:

private boolean impl$isAssignableFromOrInterface(final Class<?> baseClass, final Class<?> clazz) {
    return clazz.isInterface() || baseClass.isAssignableFrom(clazz);
}

I threw a todo comment on it for now but I can still make changes if needed

[gabizou]

Remove unnecessary todo comment on the ClassInheritanceMultiMapMixin.