I have come across a class that has an immutable property:

MyObject[] allObjs

The property is initialized like this:

List<MyObject> objs = createAllMyObjects();
allObjs = objs.toArray(new MyObject[objs.size()]);

When it is exposed through the accessor, it's done as a List:

public List<MyObject> getAllMyObjects() {
    return Collections.unmodifiableList(Arrays.asList(allObjs));
}

Why would a programmer do this? Is there a benefit that I don't know about?

Performance is not a concern, as the array of objs will only ever number in a few dozen elements.

It seems that we are going round and round in circles.

The class is a sort of factory, so it's got a private constructor and exposes only static methods (not sure if this could be a reason for the madness).