MSB4168: The item "{0}" of type "{1}" does not define a value for the metadata in the expression "{2}". This expression is ...

MSB4168: The item "{0}" of type "{1}" does not define a value for the metadata in the expression "{2}". This expression is used in the target output for target "{3}". If a target declares outputs that are transforms, all items in the transform must have a value for the metadata in the transform.