[bug] Value conversion does not work properly in API platform

For example, when having `http://localhost:9555/api/o/v1/test/12?name=fff1` with the body `{"prop1": "prop 1"}` where value `12` is a number also passed as part of the response, then the returned response looks like

`{
"id": "12",
"prop1": "prop 1",
"name": "fff1"
}`

where 12 is a string instead of the number