If only one subclasses is set, it will never be active according to the default code in Sonata\AdminBundle\Admin

[ima-tech]

I was looking through Sonata Admin code and I was having problems to use subclasses. I found out that in " Sonata\AdminBundle\Admin ", the code is the following :

    public function hasActiveSubClass()
    {
        if (count($this->subClasses) > 1 && $this->request) {
            return null !== $this->getRequest()->query->get('subclass');
        }

        return false;
    } 

In my opinion, it should be bigger or equal than 1 or bigger than 0. If not, it means that an Admin class can only be subclassed by more than one subclass.

[michelsalib]

Can you open a PR ?