subscriber able to receive message even though service account is disabled.

[zhumin8]

Filing an issue here for part of issuer reported in https://github.com/GoogleCloudPlatform/spring-cloud-gcp (referred as second issue in original comments) that's relevant here.
Application receives a message successfully from subscription, even though service account is disabled

@mayur-solace provided reproducer and steps here: GoogleCloudPlatform/spring-cloud-gcp#2158 (comment) (Note that dispite the class name suggests, this reproducer is with client library and did not use Spring Cloud GCP)