for bug 549457
) we adjusted the JDT auto-build to do a full workspace build if the JDT core settings of a project changed (.settings/org.eclipse.jdt.core.prefs changes). Mostly, this ensures that retrieving new settings from a versioning system (one integrated in the IDE) will result in a build.
If your plug-ins generate this settings file, be aware that this generation will trigger a full workspace build. I.e. if you are changing the settings file and then building the workspace in your code, you can remove the building part (in case auto-build is on). We also advise you to avoid re-generating the settings file with the same contents, since that will now trigger an unnecessary full build.
For now, if the new behavior is incompatible with your plug-ins, it can be switched off with the following VM property:
We plan to remove this option in a future release ( > 4.13).