public String findIndefiniteField() {
        String indefinite = patternFilter.findIndefiniteField();
        if (indefinite != null)
            return indefinite;
        return entryFilter.findIndefiniteField();
    }
Return a string describing an ANY or UNKNOWN field, or null if there is no such field.
clients/src/main/java/org/apache/kafka/common/acl/AclBindingFilter.java