@Override
	public Object getParent(Object element) {
		if (element instanceof IFile) {
			IFile file = (IFile) element;
			return file.getProject();
		} else if (element instanceof String) {
			String task = (String) element;
			return this.taskToFileMap.get(task);
		} else if (element instanceof AliasTask) {
			AliasTask alias = (AliasTask) element;
			return this.taskToFileMap.get(alias.task);
		}
		return null;
	}