Review

When a DataOutputStream instance wraps an underlying ByteArrayOutputStream instance,
it is recommended to flush or close the DataOutputStream before invoking the underlying instances's toByteArray().
Also, it is a good practice to call flush/close explicitly as mentioned for example here.
This pull request adds a flush method before calling toByteArray().

• missing/call

org/eclipse/paho/client/mqttv3/internal/wire/MqttUnsubscribe.java

getPayload()

class MqttUnsubscribe {
	public byte[] getPayload() throws MqttException {
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		DataOutputStream dos = new DataOutputStream(baos);
		for (int i=0; i<names.length; i++) {
			encodeUTF8(dos, names[i]);
		}
		return baos.toByteArray();
	}

}

class FlushStreamWithByteBeforeGetBytes {
  byte[] pattern(byte b) throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    DataOutputStream dos = new DataOutputStream(baos);
    dos.write(b);
    dos.flush();
    return baos.toByteArray();
  }
}