ParseObject query returning a null list + CurrentModificationException

[SeloSlav]

Why is this returning a ConcurrentModificationException? The class name is correct. I definitely have a connection to the database... Is this a known issue?

ParseQuery<ParseObject> query = ParseQuery.getQuery("Request");
        query.findInBackground(new FindCallback<ParseObject>() {
            @Override
            public void done(List<ParseObject> requestList, ParseException e) {
                for (ParseObject requestObject : requestList) {
                    requestList.add(requestObject);
                }
                model.addAttribute(requestList);
                log.info(String.valueOf(requestList));
            }
        });

I get the following exception:

[WARNING] 
java.util.ConcurrentModificationException
    at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
    at java.util.ArrayList$Itr.next(ArrayList.java:851)
    at com.nnit.automation.controller.IndexController$1.done(IndexController.java:49)
    at org.parse4j.ParseQuery$FindInBackgroundThread.run(ParseQuery.java:623)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

This seems to work fine on Android but not on my Springboot web application. I'm using the latest SNAPHSOT build:

        <dependency>
            <groupId>com.github.thiagolocatelli</groupId>
            <artifactId>parse4j</artifactId>
            <version>1.5-SNAPSHOT</version>
        </dependency>