Ok I'm making progress. I've been able to successfully convert this
```
{
  "DockerVersion": "1.9.0-dev",
  "VirtualSize": 188359297,
  "Size": 0,
  "Author": "",
  "Created": "2015-09-10T08:30:53.26995814Z",
  "GraphDriver": {
    "Name": "aufs",
    "Data": null
  }
}
```
Into this
```
class TestClass
  JSON.mapping({
    docker_version: { key: 'DockerVersion', type: String },
    virtual_size: { key: 'VirtualSize', type: Int32 },
    size: { key: 'Size', type: Int32 },
    author: { key: 'Author', type: String },
    created: { key: 'Created', type: String },
    graph_driver: { key: 'GraphDriver', type: class },
  })
end
```