public Builder descriptorWriteCallback(@NonNull UUID characteristicUUID,
                                               @NonNull UUID descriptorUUID,
                                               @NonNull RxBleDescriptorWriteCallback writeCallback) {
            Map<UUID, RxBleDescriptorWriteCallback> descriptorCallbacks = descriptorWriteCallbacks
                    .get(characteristicUUID);
            if (descriptorCallbacks == null) {
                descriptorCallbacks = new HashMap<>();
                descriptorWriteCallbacks.put(characteristicUUID, descriptorCallbacks);
            }
            descriptorCallbacks.put(descriptorUUID, writeCallback);
            return this;
        }
Set a {@link Function} that will be used to handle descriptor writes for descriptors with a given UUID. The
function should return a Completable that completes when the write completes. Calling this method is not required.
@param characteristicUUID UUID of the characteristic that the descriptor is used in
@param descriptorUUID UUID of the descriptor that the callback will handle reads for
@param writeCallback The callback
mockrxandroidble/src/main/java/com/polidea/rxandroidble2/mockrxandroidble/RxBleConnectionMock.java