string length not taken into account on id while using Yaml driver

---
# Entities.Stock.dcm.yml
Entities\Stock:
  type: entity
  table: stocks
  id:
    id:
      type: string
      length: 10
      generator:
        strategy: NONE
  fields:
    nature:
      type: string
      length: 10
    name:
      type: string
      length: 40
    creationDate:
      name: creation_date
      type: datetime
    owner:
      type: string
      length: 8

CREATE TABLE stocks (id VARCHAR(255) NOT NULL, nature VARCHAR(12) NOT
NULL, name VARCHAR(40) NOT NULL, creationDate DATETIME NOT NULL, owner
VARCHAR(8) NOT NULL, PRIMARY KEY(id)) ENGINE = InnoDB