User-level description: it should be possbile to
display significant folders in project with their
role in project. E.g. 
/projectHome     - 'other' sources
/projectHome/src - Java sources root
/projectHome/web - Document Base
/projectHome/api - javadoc overviews
...

This can be used in project wizard and in project
customizer. There should also be add/remove button
to add files/folders and categorize them by role
and it should be possbile to change the role of an
existing file/folder to a different role (the list
of roles may be limited to roles that make sense
for given file/folder)

API -level:
The list of existing folders and their roles
should be based on /Containers. There needs to be
representation of 'role' with a display name. For
every entry in Containers list it needs to be
possible to determine its role. The proposal is to
use recognizers for representing the role. A
recognizer needs to be able to recognize an entry
in Containers list. It needs to be able to
recognize a folder/file that can be supported by
it and add a container for it.