Accessing VirtualMachine->snapshot when there are not snapshots creates an infinite loop

[rgrwkmn]

vm-123 has no snapshots.

$vm = $vhost->findOneManagedObject('VirtualMachine', 'vm-123');
$vm->snapshot; //infinite loop
$vm->hasSnapshots(); // tries to get $this->snapshot, infinite loop

The problem is that when there are no snapshots for the virtual machine, vSphere does not return a snapshot index at all. I verified this by inspecting the result from PropertyCollector->collectPropertiesFor. When it tries to access snapshot on that object it just starts the process all over again and loops until the maximum amount of nested function calls is reached.

Luckily, checking for the existence of snapshot with isset in Service->getQueriedProperty solves the issue:

    private function getQueriedProperty($method, $arguments) {
        $propertyToRetrieve = $this->generateNameForThePropertyToRetrieve($method);
        $content = $this->getServiceContent();
        if (isset($content->$propertyToRetrieve)) return $content->$propertyToRetrieve;
        $managedObject = $arguments[0];
        $foundManagedObject = $this->findOneManagedObject($managedObject->getReferenceType(),
            $managedObject->getReferenceId(), array($propertyToRetrieve));
        if (!isset($foundManagedObject->$propertyToRetrieve)) return null;
        return $foundManagedObject->$propertyToRetrieve;
    }

I'm going to make a pull request for the fix.