Add sample values to swagger page

[RichoDemus]

Currently the swagger page does not have proper sample/default values for its entities, instead they look like this:

{
  "id": "null",
  "page": "null",
  "data": "null"
}

preferably it would look something like this:

{
  "id": "0cfbef3e-a145-4cb0-b257-f4ce96bce94c",
  "page": 1,
  "data": "{"foo":"baar"}" // or however json in json would look
}

the swagger spec is located at: server/swagger/src/main/resources/api-specification.yaml