jsv4 doesn't check if string is empty. It return true if strlen(field)== 0

No validation on string minimum length ?? 
If someone sends a string field, but it's empty, for example {
  "address": {
    "streetAddress": "21 2nd Street",
    "city": ""
  },
  "phoneNumber": [
    {
      "location": "home",
      "code": 44
    }
  ]
}

city is empty, but is validated true 
