Json Schema to json conversion library in java or groovy

I have Json schema as input I want to know whether there is a method by which I can generate sample json output. Do we have any such library in java which I can use?

{
"title": "InputSchema",
"type": "object",
"properties": {
    "firstName": {
        "type": "string"
    },
    "lastName": {
        "type": "string"
    },
    "age": {
        "description": "Age in years",
        "type": "integer",
        
    }
},
"required": ["firstName", "lastName"]
}

output => 

{     
  "firstName" : "FirstName",
   "lastName" : "LastName"
}