[jdt-core-dev] Breaking change in JavaModel

["Philippe P Mulet" <philippe_mulet@xxxxxxxxxx>]

In the process of adapting the JavaModel to the platform background
autobuild support, we have to break some assumptions.

The JavaModel used to be listening to PRE_AUTO_BUILD notifications:
- reconcile classpath changes (add/delete classpath markers)
- perform a few updates in the JavaModel such as project additions/removals
- broadcast classpath changes (roots added/removed...).
- broadcast any Java operation changes.

Then during the POST_CHANGE, we were re-broadcasting again these changes,
but no longer touch markers since it is forbidden at this sage.

Since PRE_AUTO_BUILD and POST_CHANGE are no longer happening in order, and
in same thread (once platform background support is enabled), we have a
major issue in JavaModel consistency. The only viable solution for us is to
separate the marker creation in PRE_AUTO_BUILD from the JavaModel update in
POST_CHANGE.

As a consequence, no more Java deltas are going to be notified during
PRE_AUTO_BUILD. Only POST_CHANGE events will be notified.
This evolution is conditionned by the platform change, and we would like to
hear about clients which are impacted by these changes.

Also see platform change at:
http://dev.eclipse.org/viewcvs/index.cgi/%7Echeckout%7E/platform-core-home/documents/plan_concurrency_listeners.html