Can't generate code with default value in spec

[mohsen1]

This issue was raised in Swagger Editor swagger-api/swagger-editor#376

---
swagger: '2.0'
info:
  version: 1.0.0
  title: test
  description: test
schemes:
  - http
host: example.com
basePath: /test
paths:
  /:
    get:
      responses:
        200:
          description: Echo GET
          schema:
            $ref: '#/definitions/echo'
definitions:
  echo:
    properties:
      id:
        type: integer
        min: 0
        default: 1 # comment this line then code-gen is ok