principalSubject property
A string that represents the principal_subject that is associated with the identity.
Unlike principal_email, principal_subject supports principals that
aren't associated with email addresses, such as third party principals.
For most identities, the format is
principal://iam.googleapis.com/{identity pool name}/subject/{subject}.
Some GKE identities, such as GKE_WORKLOAD, FREEFORM, and GKE_HUB_WORKLOAD,
still use the legacy format serviceAccount:{identity pool name}[{subject}].
Implementation
core.String? principalSubject;