Resource Deltas for External Folders
The resources plug-in broadcasts resource change events for files and folders in the workspace. This allows clients to react to changes that occur in those resources, and in the underlying file system. There is no way to receive resource change events for files and folders in the file system that do not belong to the workspace.
In the Java development tools, it would be useful to be able to add folders outside the workspace to a build path of a Java project. This is not currently supported because there is no way to incrementally track changes to those external folders during a build. This is acceptable if the contents of the external folders never change, but will not be acceptable for end users when the folders are modified. The expectation is that the Java builder will do the right thing, and react to changes in the external folders.
One notable example of this requirement comes from plug-in developers using EMF-generated