Syntax for list preferences

[nikolasr200]

my application json

[
    {
        "type":"group",
        "title":"Measurement Units",
        "key":"measurement_units",
        "description":"Define which measurement unit is prefered",
        "items":[
            {
                "type":"radio",
                "items":[
                    {
                        "value":"kilometers_litres",
                        "title":"Use kilometers / litres"
                    },
                    {
                        "value":"miles_gallons",
                        "title":"Use miles / gallons"
                    }
                ],
                "default":"kilometers_litres",
                "title":"Measurement unit",
                "key":"measurement_unit",
                "name":"measurementunit"
            }
        ]
    }
]

and the error

mypath\plugins\cordova-plugin-app-preferences\bin\li
b\mobile_preferences.js:274
                config.attrs[attr] = config.attrs[attr].join ('|');
                                                        ^
TypeError: Object @apppreferences_strings/measurementunit has no method 'join'
    at androidBuildNode (mypath\plugins\cordova-plugin-app-preferences\bin\lib\mobile_preferences.js:274:43)
    at mypath\plugins\cordova-plugin-app-preferences\bin\lib\mobile_preferences.js:287:4
    at Array.forEach (native)
    at androidBuildNode (mypath\plugins\cordova-plugin-app-preferences\bin\lib\mobile_preferences.js:286:19)
    at mypath\plugins\cordova-plugin-app-preferences\bin\lib\mobile_preferences.js:312:3
    at Array.forEach (native)
    at Object.androidBuildSettings (mypath\plugins\cordova-plugin-app-preferences\bin\lib\mobile_preferences.js:303:13)
    at mypath\plugins\cordova-plugin-app-preferences\bin\build-app-settings.js:80:32
    at fs.js:272:14
    at C:\Users\project\AppData\Roaming\npm\node_modules\cordova\node_modules\cordova-lib\node_modules\npm\node_modules\graceful-fs\graceful-fs.js:103:5