[ ] route to instance if an instance identifier is provided
[ ] deprecate old signatures
Ensure proper error is thrown if target instance is specified but not found:
If a specific target app parameter was set, but either the app or app instance is not available then the ResolveError.TargetAppUnavailable or ResolveError.TargetInstanceUnavailable errors MUST be returned.
Ensure proper error is thrown if target instance is specified but not found: