Represents a role or capability attribute on the resource that maps to a relation on the resource instance itself (:self, the default) or an external object (e.g., target: "platform:main" -> platform:main#<role>@user:<id>).
:self
target: "platform:main"
platform:main#<role>@user:<id>
@type t() :: %AshAuthzed.ExternalRole{ __spark_metadata__: term(), attribute: atom(), role_mapping: map(), subject_id: atom(), subject_type: String.t(), target: String.t() | :self | nil }