Validation is not working if form is not filled

Hi ,
I am using brutusin:json-forms in my project to create form dynamically. But I have found one issue with validation. If form is empty then validation is not working for below json
JSON Data=>

```javascript
{
"title": "Person",
"type": "object",
"properties": {
"firstName": {
"type": "string"
},
"lastName": {
"type": "string"
},
"age": {
"description": "Age in years",
"type": "integer",
"minimum": 0
}
},
"required": ["firstName", "lastName"]
}
```
Please help me to fix this issue.