Symfony\Component\DependencyInjection\Definition::isAbstract PHP Method

    public function isAbstract()
    {
        return $this->abstract;
    }

 public function validate(Definition $definition) : bool
 {
     if (!$definition->isPublic() || $definition->isAbstract()) {
         return false;
     }
     if (null === $definition->getClass() || !class_exists($definition->getClass())) {
         return false;
     }
     return true;
 }