From forum post: http://forum.springsource.org/showthread.php?t=101376
It appears we have a problem with installing a plugin that pulls in another plugin. As an example, try to install multi-tenant-core which will pull in falcone-util. If you install via the prompt, it is fine. If you try to install via the plugin manager you get an error like the one shown below.
See how application.properties is considered out of sync. Did we not refresh the resource for application.properties in eclipse after updating it with a line for multi-tenant-core?