al value in order to produce a result that can be assigned to an instance’s field.</p><p>Every instance field has a type, as defined in the template, every attribute has a
<a href=https://github.com/istio/api/blob/master/policy/v1beta1/value_type.proto>type</a>, and every attribute expression has a type.
You can only assign type-compatible expressions to any given instance fields. For example, you can’t assign an integer expression
to a string field. This kind of strong typing is designed to minimize th