Source identifier in form <namespace>/<name>, e.g. 'hashicorp/google'. GoogleProvider returns kProviderSource. Synth emits this under terraform.required_providers.<providerName>.source.
<namespace>/<name>
'hashicorp/google'
GoogleProvider
kProviderSource
terraform.required_providers.<providerName>.source
@override String get source => 'hashicorp/time';