{
  "manifest_version": 2,
  "name": "json-mime-type-override",
  "version": "1.4",

  "description": "Allow to override any content type containing json to application/json",

  "applications": {
    "gecko": {
      "strict_min_version": "52.0"
    }
  },

  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],

  "background": {
    "scripts": ["main.js"]
  }
}

{
  "manifest_version": 2,
  "name": "json-mime-type-override",
  "version": "1.4",

  "description": "Allow to override any content type containing json to application/json",

  "applications": {
    "gecko": {
      "strict_min_version": "52.0",
      "strict_max_version": "57.*"
    }
  },

  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],

  "background": {
    "scripts": ["main.js"]
  }
}

Set max version to Firefox 57 while the feature is natively implemented in Firefox 58+
Set max version to Firefox 57 while the feature is natively implemented in Firefox 58+
