What is the purpose of fetch.json file inside cordova plugins folder?

File fetch.json created inside plugins folder after cordova plugin add executed first time. This file also modified each time I add/remove plugins.

What purpose of this file exactly?
What tools use this file, when and why?
Is there a way to restore plugins using fetch.json (try not to place plugins into repositiory)?
Where can I find some docs about content of this file?

Content of fetch.json:

{
    "com.phonegap.plugins.PushPlugin": {
        "source": {
            "type": "git",
            "url": "https://github.com/phonegap-build/PushPlugin.git",
            "subdir": "."
        },
        "is_top_level": true,
        "variables": {}
    },
    "cordova-plugin-file": {
        "source": {
            "type": "registry",
            "id": "cordova-plugin-file"
        },
        "is_top_level": true,
        "variables": {}
    }
}

Solution

Looks like this file tracks installed plugins, their origin and revision, like npm package.json dependencies does, but for plugman. I guess and hope this should migrate to the npm standard soon.

This file is updated on cordova add/remove plugins (https://github.com/apache/cordova-lib/blob/e4e5904619bab05705d62bce92a4c4cd0d45bb82/cordova-lib/src/cordova/plugin.js#L272)

When we cordova prepare, cordova reads plugin list from plugins/ios.json (for ios), then, for each one :

get the plugin infos from plugins/fetch.json
try to find the plugin locally

looks like its not possible to restore plugins with this file. My workflow is :

define plugins dependencies in config.xml
remote platforms and empty plugins folder
run cordova platform add xxx

this will refetch plugins as defined in config.xml

Looks like the only doc is the source code : https://github.com/apache/cordova-lib/search?utf8=%E2%9C%93&q=fetch