PowerBiNodeSDK (1.0) - setAllConnections ---Error: Required 'connectionString' property is missing

It is quite clear and simple to create a client

var credentials = new msrest.TokenCredentials('cAY0b0dCSSbg0oL3nHcgMScnrB...lw==', 'AppKey');
var client = new powerbi.PowerBIClient(credentials);

To trigger the setAllConnection function

client.datasets.setAllConnections('pow....','112ef...','a1baf74f...',mparameters,function (err, result, request, response) {
console.log(err );});

Sadly i can't generate the 4. parameter ('mparameters')

var mparameters = {theMissungKey: {"connectionString": "data source=yourDB.database.windows.net;initial ....

I have no Clue what the name of the first Key "theMissingKey" could be.

I always get this error message

Error: Required 'connectionString' property is missing or misspelled

Any ideas ?

Thank you michael