# Functions
CredentialsTokenSource returns an impersonated CredentialsTokenSource configured with the provided config and using credentials loaded from Application Default Credentials as the base credentials.
IDTokenSource creates an impersonated TokenSource that returns ID tokens configured with the provided config and using credentials loaded from Application Default Credentials as the base credentials.
# Structs
CredentialsConfig for generating impersonated credentials.
IDTokenConfig for generating an impersonated ID token.