public function checkCredentials($credentials, UserInterface $user)
    {
        return $this->userPasswordEncoderFactory->isPasswordValid($user, $credentials->getPassword());
    }
public function checkCredentials($credentials, UserInterface $user)
    {
        return $this->userPasswordEncoderFactory->isPasswordValid($user, $credentials->getPassword());
    }
public function checkCredentials ( $ credentials , UserInterface $ user ) { return $ this -> userPasswordEncoderFactory -> isPasswordValid ( $ user , $ credentials -> getPassword ( ) ) ; }
4) Returns true if the credentials are valid.
For token based requests, facebook, etc.  Token are validate by a 3rd party provider in the getUser function

@param CredentialEmailModel $credentials
@param UserInterface $user
@return bool
4 ) Returns true if the credentials are valid . For token based requests facebook etc . Token are validate by a 3rd party provider in the getUser function