API query to list all project areas an user belongs to

Since the question does not provide what the purpose of the endeavor is, here some summary of what could be looked at:

1. The API landing page is here: https://jazz.net/wiki/bin/view/Deployment/CLMProductAPILanding check the available APIs
   
2. The 4 APIS that are documented here contain the Reportable REST API and the OSLC API. The reportable RESt API mentions https://jazz.net/wiki/bin/view/Main/RqmApi#Project_Area_Metadata_Viewer_AN1 and also in 7.x filter capabilities. This might be a way. I am not sure if the OSLC API provides this information.
   
3. ETM does not provide a JAVA API like EWM does, BUT parts of the EWM API covers the Jazz Foundation and it might be possible to use that against ETM. https://rsjazz.wordpress.com/2012/12/09/analyzing-a-aroject-areas-members-and-roles-using-the-plain-java-client-libraries/ contains examples for finding such information in EWM.
4. The Jazz Foundation API https://jazz.net/wiki/bin/view/Main/DraftTeamProcessRestApi , https://jazz.net/wiki/bin/view/Main/JazzRESTServicesMain might provide the desired information. I noticed that some of the user related queries do not work any more due to concerns with privacy.
   

Unit test to the solution:

@Test
  public void run() throws TeamRepositoryException {


    TeamPlatform.startup();
    try {


      String repositoryURI = "" ;    //Your Repository Here
      String userId = "" ;                 //Your username Here
      String password = " " ;            //Your Password

     String memberUser = "" ;               // The user for whom you want the project areas to be listed

      ITeamRepository teamRepository = TeamPlatform.getTeamRepositoryService().getTeamRepository(repositoryURI);
      teamRepository.registerLoginHandler(new LoginHandler(userId, password));
      teamRepository.login(null);

      System.out.println("Logged in as: " + teamRepository.loggedInContributor().getName());

      if (projectAreaName == null) {
        // For all project areas
        IProcessItemService itemService =
            (IProcessItemService) teamRepository.getClientLibrary(IProcessItemService.class);
        List pAreas = itemService.findAllProjectAreas(null, null);
        for (Iterator iterator = pAreas.iterator(); iterator.hasNext();) {
          IProjectArea projectArea = (IProjectArea) iterator.next();
        
          IContributor user = teamRepository.contributorManager().fetchContributorByUserId(memberUser , null);

          if (projectArea.hasMember(user)) {
            System.out.println(projectArea.getName());
          }

        }
      }

      teamRepository.logout();

    }
    catch (TeamRepositoryException x) {
      x.printStackTrace();
    }
    finally {
      TeamPlatform.shutdown();
    }

  }