private function initResolvers()
    {
        $this->groupOptionsResolver = new OptionsResolver();
        $this->groupOptionsResolver
            ->setDefaults([
            	'name'     => null,
            	'label'    => null,
            	'icon'     => null,
            	'position' => 1,
            	'domain'   => 'messages',
            	'route'    => null,
            ])
            ->setAllowedTypes('name',     'string')
            ->setAllowedTypes('label',    'string')
            ->setAllowedTypes('icon',     'string')
            ->setAllowedTypes('position', 'int')
            ->setAllowedTypes('domain',   'string')
            ->setAllowedTypes('route',    ['string', 'null'])
        ;

        $this->entryOptionsResolver = new OptionsResolver();
        $this->entryOptionsResolver
            ->setDefaults([
            	'name'     => null,
            	'label'    => null,
            	'route'    => null,
            	'position' => 1,
                'domain'   => 'messages',
            	'resource' => null,
            ])
            ->setAllowedTypes('name',     'string')
            ->setAllowedTypes('label',    'string')
            ->setAllowedTypes('route',    'string')
            ->setAllowedTypes('position', 'int')
            ->setAllowedTypes('domain',   'string')
            ->setAllowedTypes('resource', 'string')
        ;
    }