MavenActionUtil.getMavenProject(e.getDataContext()) is Null?

I want to develop a plugin just like "Maven Helper".  I have to get the "MavenProject" object before I can do some biz logic.  But I found the MavenProjectsManager is null (I use it in a maven project.)? Could someone give me some dev guide about this ? Thanks!

    public void actionPerformed(AnActionEvent e) {
        Project project = e.getData(PlatformDataKeys.PROJECT);
        VirtualFile file = e.getData(PlatformDataKeys.VIRTUAL_FILE);

        if (file == null || project == null) {
            return;
        }
        String fileName = file.getName();

        if (!fileName.endsWith(POM_XML)) {
            return;
        }

        final MavenProjectsManager projectsManager = MavenProjectsManager.getInstance(project);