Extension point to tell the Other sources project subnode to exclude the given folder name in
src/main and src/test. It is assumed that implementing this interface is associated
with implementation of a NodeFactory providing special handling for such folder.
To be registered in project lookup.
Related to JavaLikeRootProvider but only handling the Other sources node display.
Note: the api is a bit simplistic for performance reasons, eg. if user reconfigures the src/main/webapp content to a different location in pom.xml we silently assume that
src/main/webapp doesn't exist then.