Sim, finalmente descobri que o problema é com
John.orm.php arquivo que será gerado quando eu executei php bin/console doctrine:generate:entity Eu criei a classe Entity usando o seguinte comando
php bin/console doctrine:generate:entity
Em seguida, ele solicitará
Welcome to the Doctrine2 entity generator
This command helps you generate Doctrine2 entities.
First, you need to give the entity name you want to generate.
You must use the shortcut notation like AcmeBlogBundle:Post.
The Entity shortcut name: AppBundle:John
Determine the format to use for the mapping information.
Configuration format (yml, xml, php, or annotation) [annotation]: php
Instead of starting with a blank entity, you can add some fields now.
Note that the primary key will be added automatically (named id).
Available types: array, simple_array, json_array, object,
boolean, integer, smallint, bigint, string, text, datetime, datetimetz,
date, time, decimal, float, binary, blob, guid.
New field name (press <return> to stop adding fields): id
Field "id" is already defined.
New field name (press <return> to stop adding fields): username
Field type [string]: string
Field length [255]:
Is nullable [false]: true
Unique [false]: false
New field name (press <return> to stop adding fields): password
Field type [string]:
Field length [255]:
Is nullable [false]: true
Unique [false]:
New field name (press <return> to stop adding fields): dob
Field type [string]: date
Is nullable [false]: true
Unique [false]:
New field name (press <return> to stop adding fields):
Entity generation
created .\src\AppBundle/Entity/John.php
created .\src\AppBundle/Resources/config/doctrine/
created .\src\AppBundle/Resources/config/doctrine/John.orm.php
> Generating entity class G:\XAMPP\htdocs\project\src\AppBundle\Entity\John.php:
OK!
> Generating repository class G:\XAMPP\htdocs\project\src\AppBundle\Repository\J
ohnRepository.php: OK!
> Generating mapping file G:\XAMPP\htdocs\project\src\AppBundle\Resources\config
\doctrine\John.orm.php: OK!
Everything is OK! Now get to work :).
G:\XAMPP\htdocs\project>
E após o sucesso, ele criará uma classe de entidade em
AppBundle\Entity; pasta e classe de repositório em AppBundle\Repository; também irá gerar John.orm.php em AppBundle\Resources\config\doctrine\John.orm.php Depois de excluir o arquivo John.orm.php se eu executar
php bin/console doctrine:schema:update --force então ele irá gerar tabelas. 
