Error code 400 trying to sign provided bytes

[shoaib]

Hi,

I have been getting this error for sign URL (GCP Storage). 
java.io.IOException: Error code 400 trying to sign provided bytes: Invalid form of account ID <PROJECT_ID>.svc.id.goog. Should be [Gaia ID |Email |Unique ID |] of the account.

this is the Java code that i have.

I have also assigned 

roles/iam.serviceAccountTokenCreator

to the App Engine default service account and to the service account used for this microservice.
any help would be appreciated.

Thanks