private void unmap(K key) {
        fulfillmentMap.remove(key);

        ApiRequestScope lookupScope = handler.lookupStrategy().lookupScope(key);
        OptionalInt destinationBrokerId = lookupScope.destinationBrokerId();

        if (destinationBrokerId.isPresent()) {
            fulfillmentMap.put(new FulfillmentScope(destinationBrokerId.getAsInt()), key);
        } else {
            lookupMap.put(handler.lookupStrategy().lookupScope(key), key);
        }
    }
Disassociate a key from the currently mapped brokerId. This will send the key
back to the Lookup stage, which will allow us to attempt lookup again.
clients/src/main/java/org/apache/kafka/clients/admin/internals/AdminApiDriver.java