This is a common bug across Java in general, apparently. There are many workarounds, none of which have worked for me - which makes me think it's a problem with the Plain Java Client Library itself.

I basically followed the tutorial on https://jazz.net/library/article/1229.
Using IntelliJ 14.1.4, RTC Server 5.0.2 (Both the client jars and server, I checked)
Throws an error on

 IItemQueryPage queryPage = buildClient.queryItems(query, new Object[] { definition.getItemId() },
                IQueryService.ITEM_QUERY_MAX_PAGE_SIZE, myProgressMonitor);

The problem occurs with OR without debugging.
Some string literals changed for safety.

public class Main {
    static final String USER = "ABCD";
    static IProgressMonitor myProgressMonitor;
    static final String SITE = "https://contonso.com/jazz";
    static final String pass = "1234";
    public static void main(String[] args) {
        org.apache.log4j.BasicConfigurator.configure();
        TeamPlatform.startup();

        try {

            ITeamRepository repo = Login(pass);
            if (repo == null) throw new Exception("Could not login");
            ITeamBuildClient buildClient = (ITeamBuildClient)repo.getClientLibrary(ITeamBuildClient.class);
            IBuildDefinition definition = buildClient.getBuildDefinition("my.build.id", myProgressMonitor);

            getWIs(buildClient, definition);

        } catch(Exception ex) {System.err.println(ex.getMessage());} finally {
            TeamPlatform.shutdown();
        }
        System.exit(0);
    }
    public static ITeamRepository Login(final String pass) {

        ITeamRepository repo = TeamPlatform.getTeamRepositoryService().getTeamRepository(SITE);
        repo.registerLoginHandler(new ILoginHandler2() {
            @Override
            public ILoginInfo2 challenge(ITeamRepository repo) {
                return new UsernameAndPasswordLoginInfo(USER, pass);
            }
        });
        try {
            repo.login(myProgressMonitor);

            return repo;
        } catch (TeamRepositoryException e) {
            e.printStackTrace();
            return null;
        }

    }
    public static void getWIs(ITeamBuildClient buildClient, IBuildDefinition definition) throws TeamRepositoryException {
        IBaseBuildResultQueryModel.IBuildResultQueryModel buildResultQueryModel = IBaseBuildResultQueryModel.IBuildResultQueryModel.ROOT;
        IItemQuery query = IItemQuery.FACTORY.newInstance(buildResultQueryModel);
        IPredicate predicate = (buildResultQueryModel.buildDefinition()._eq(query.newItemHandleArg()))._and(
                buildResultQueryModel.personalBuild()._isFalse())._and(
                buildResultQueryModel.buildState()._eq(BuildState.COMPLETED.name()));

        query.filter(predicate);
        query.orderByDsc(buildResultQueryModel.buildStartTime());

        IItemQueryPage queryPage = buildClient.queryItems(query, new Object[] { definition.getItemId() },
                IQueryService.ITEM_QUERY_MAX_PAGE_SIZE, myProgressMonitor);
        while (queryPage.hasNext()) {
            queryPage = (IItemQueryPage) buildClient.fetchPage(queryPage.getToken(), queryPage.getNextStartPosition(), 1, myProgressMonitor);
            System.out.println(queryPage.toString());
        }


    }

}