I have with JIRA 3.0.3, built some plugin for In-House requirements (Reports, Workflows FunctionProvider, Components and Portlet) and too made some patche in JIRA Distribution using edit-webapp folder.

Performing the migration from 3.0.3 to 3.4.x, I try to use the Webwork Module available since 3.1.x, but is there a way to provide through an Atlassian Plugin resources files like images required for a Portlet (corner_* image file), a new or override JSP file ...