Bug 120544 [build path] Editing external source folder does not persist
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/BuildPathsBlock.java
public static interface IRemoveOldBinariesQuery {
		
		/**
		 * Do the callback. Returns <code>true</code> if .class files should be removed from the
		 * old output location.
		 * @param oldOutputLocation The old output location
		 * @return Returns true if .class files should be removed.
		 * @throws OperationCanceledException
		 */
		boolean doQuery(IPath oldOutputLocation) throws OperationCanceledException;
		
	}
	private IWorkspaceRoot fWorkspaceRoot;