public Builder characteristicWriteCallback(@NonNull UUID characteristicUUID,
                                                   @NonNull RxBleCharacteristicWriteCallback writeCallback) {
            characteristicWriteCallbacks.put(characteristicUUID, writeCallback);
            return this;
        }
Set a {@link Function} that will be used to handle characteristic writes for characteristics 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 callback will handle reads for
@param writeCallback The callback
mockrxandroidble/src/main/java/com/polidea/rxandroidble2/mockrxandroidble/RxBleConnectionMock.java