This is easy enough to find for the Java API, provided you follow the hint in https://rsjazz.wordpress.com/2013/03/20/understanding-and-using-the-rtc-java-client-api/ to setup the RTC Eclipse client with the SDK.

That allows to search e.g. for the stuff you use un your question and in 2 minute you can find the JUnit test cases with the working code. Foe example you find com.ibm.team.process.internal.client.tests.ProcessWorkingCopyTests.testAddToAndRemoveFromProjectAreaAccessList()


with this code:

    public void testAddToAndRemoveFromProjectAreaAccessList() throws TeamRepositoryException {
        // This will be the list that we expect at the end: user1, guest1, and guest2
        List expectedUsers = new ArrayList();
        // First, set up the project area by manually adding members to the access list.
        IContributor user1 = repo.contributorManager().fetchContributorByUserId(TestUserNames.TEST_JAZZ_USER1, null);
        expectedUsers.add(user1);
        IContributor user2 = repo.contributorManager().fetchContributorByUserId(TestUserNames.TEST_JAZZ_USER2, null);
        IReadAccessListHandle accessHandle = fProjectArea.getReadAccessList();
        IReadAccessList accessList = (IReadAccessList) repo.itemManager().fetchCompleteItem(accessHandle, IItemManager.REFRESH, null).getWorkingCopy();
        accessList.addContributors(new IContributorHandle[] { user1, user2 });
        getProcessItemService().save(accessList, null);

    IContributor guest1 = repo.contributorManager().fetchContributorByUserId(TestUserNames.TEST_JAZZ_GUEST1, null);
    expectedUsers.add(guest1);
    IContributor guest2 = repo.contributorManager().fetchContributorByUserId(TestUserNames.TEST_JAZZ_GUEST2, null);
    expectedUsers.add(guest2);

    // Make the working copy changes
    IProjectArea projectArea = getProjectAreaWithSettings();
    fWorkingCopy = (IProcessAreaWorkingCopy) getProcessItemService().getWorkingCopyManager().createPrivateWorkingCopy(projectArea);
    syncInitializeWorkingCopy(fWorkingCopy, null);
    ProjectAreaAccessControlWorkingCopy accessControl = ((ProjectAreaWorkingCopy) fWorkingCopy).getAccessControl();
    accessControl.addContributor(guest1);
    accessControl.addContributor(guest2);
    accessControl.removeContributor(user2);
    fWorkingCopy.save(null);
    fWorkingCopy.dispose();