org.eclipse.core.runtime.CoreException: Executable extension definition for "class" not found.
	at org.eclipse.core.internal.registry.ConfigurationElement.throwException(ConfigurationElement.java:62)
	at org.eclipse.core.internal.registry.ConfigurationElement.createExecutableExtension(ConfigurationElement.java:222)
	at org.eclipse.core.internal.registry.ConfigurationElementHandle.createExecutableExtension(ConfigurationElementHandle.java:55)
	at org.eclipse.ui.internal.WorkbenchPlugin$1.run(WorkbenchPlugin.java:293)
	at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:52)
	at org.eclipse.ui.internal.WorkbenchPlugin.createExtension(WorkbenchPlugin.java:288)
	at org.eclipse.ui.internal.EarlyStartupRunnable.getExecutableExtension(EarlyStartupRunnable.java:102)
	at org.eclipse.ui.internal.EarlyStartupRunnable.run(EarlyStartupRunnable.java:54)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
	at org.eclipse.ui.internal.Workbench$56.run(Workbench.java:2801)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)