Consider type "string" as a default for all the values

[DIVYA-19]

Is it possible to specify that all the values are string types?
To get output like this:

{
          "author": "Corets, Eva",
          "title":  "Maeve Ascendant",
          "genre":  "Fantasy" 
}

Instead of this:

{
          "author": {
              "_text": "Corets, Eva"
          },
          "title": {
              "_text": "Maeve Ascendant"
          },
          "genre": {
              "_text": "Fantasy"
          }
}