ClientException "failed to parse header value"

[SetNameHere]

Hi,

first of all thanks for your work on this package!

I'm trying to develop a flutter (web) application which needs to invoke access restricted Cloud Functions.

Therefore I have created a service account in my google cloud console and followed your example on how to retrieve an authenticated http client as an autonomous application.

final accountCredentials = new ServiceAccountCredentials.fromJson(r'''{ "private_key_id": "****", "private_key": "****", "client_email": "****.iam.gserviceaccount.com", "client_id": "****", "type": "service_account" }'''); var scopes = [CloudfunctionsApi.CloudPlatformScope]; AuthClient client = await clientViaServiceAccount(accountCredentials, scopes);

This seems to work fine. But when I try to use the received client to make a post request to my cloud function, I get a ClientException ("failed to parse header value").

http.Response resp = await client.post( CloudFunctiontriggerURL, body: {'data': userId});

As I understand the examples, this should work fine without specifying any headers manually in the POST function call. Correct?
However, even if I specify the header manually, I get this error.

Any help with this would be highly appreciated.

[SetNameHere]

I think I have found the key issue. I have to explicitly add the ID Token to the request.
However similar to this issue #52, the ID Token I receive within the client is always null.

Could any one tell me how I can retrieve a valid ID Token using this package?