public Optional<ApiException> exception() {
        return exception == null ? Optional.empty() : Optional.of(exception);
    }
Returns any exception while attempting to match ACL filter to delete ACLs.
If exception is empty, filtering has succeeded. See {@link #aclBindingDeleteResults()}
for deletion results for each filter.
clients/src/main/java/org/apache/kafka/server/authorizer/AclDeleteResult.java