Create some projects, delete them and you get a couple of these:

java.lang.NullPointerException
at org.jboss.tools.common.model.util.EclipseResourceUtil.getJavaProjectSrcLocations(EclipseResourceUtil.java:409)
at org.jboss.tools.common.model.filesystems.impl.FileSystemsLoader.updateSrcs(FileSystemsLoader.java:212)
at org.jboss.tools.common.model.filesystems.impl.FileSystemsLoader.update(FileSystemsLoader.java:63)
at org.jboss.tools.common.model.filesystems.impl.FileSystemsImpl.doUpdate(FileSystemsImpl.java:287)
at org.jboss.tools.common.model.filesystems.impl.FileSystemsImpl.access$4(FileSystemsImpl.java:281)
at org.jboss.tools.common.model.filesystems.impl.FileSystemsImpl$UpdateRunnable.run(FileSystemsImpl.java:265)
at org.jboss.tools.common.model.XJob.run(XJob.java:125)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)