Configures the `Kafka` custom resource to use Open Policy Agent authorization.

To use link:https://www.openpolicyagent.org/[Open Policy Agent^] authorization, set the `type` property in the `authorization` section to the value `opa`,
and configure OPA properties as required.
Strimzi uses the Open Policy Agent plugin for Kafka authorization as the authorizer.
For more information about the format of the input data and policy examples, see {OPAAuthorizer}.

.Example Open Policy Agent authorizer configuration
[source,yaml,subs=attributes+]
----
apiVersion: {KafkaApiVersion}
kind: Kafka
metadata:
  name: my-cluster
  namespace: myproject
spec:
  kafka:
    # ...
    authorization:
      type: opa
      url: http://opa:8181/v1/data/kafka/allow
      allowOnError: false
      initialCacheCapacity: 1000
      maximumCacheSize: 10000
      expireAfterMs: 60000
      superUsers:
        - CN=user-1
        - user-2
        - CN=user-3
    # ...
----
