SmackInitialization: Could not determine Smack ver

I am making an android plugin for Unity, I need to integrate XMPP in Unity so first I am trying to create a connection of XMPP and send and receive a message. It's working fine in android, I am able to send and receive message But when I export .jar file and use in Unity so I got below error while I create connection

SmackInitialization: Could not determine Smack version
  java.lang.NullPointerException: lock == null
  at java.io.Reader.<init>(Reader.java:64)
  at java.io.InputStreamReader.<init>(InputStreamReader.java:122)
  at java.io.InputStreamReader.<init>(InputStreamReader.java:57)
  at org.jivesoftware.smack.SmackInitialization.<clinit>(SmackInitialization.java:61)
  at org.jivesoftware.smack.SmackConfiguration.getVersion(SmackConfiguration.java:96)
  at org.jivesoftware.smack.ConnectionConfiguration.<clinit>(ConnectionConfiguration.java:38)
  at com.arvaan.myplugins.ToastExample.connectXMPP(ToastExample.java:99)
  at com.unity3d.player.UnityPlayer.nativeRender(Native Method)
  at com.unity3d.player.UnityPlayer.a(Unknown Source)
  at com.unity3d.player.UnityPlayer$b$1.handleMessage(Unknown Source)
  at android.os.Handler.dispatchMessage(Handler.java:98)
  at android.os.Looper.loop(Looper.java:234)
  at com.unity3d.player.UnityPlayer$b.run(Unknown Source)

I don't know what is an issue with Smack, I am new in Unity, I know how to create plugins and call method in Unity but don't know what's wrong over here.

Please check code :

public class ToastExample extends UnityPlayerActivity implements ConnectionListener, ChatManagerListener, RosterListener, PingFailedListener, StanzaListener, MessageListener, ChatMessageListener {

private static final String TAG = ToastExample.class.getSimpleName();
private AbstractXMPPConnection mConnection = null;
private ChatManager chatManager;
private Chat chat;
private Context context;
private String userName = "";
private String passWord = "";
private String objectName = "";
private static ToastExample instance;

public ToastExample() {
    this.instance = this;
}
public static ToastExample instance() {
    if (instance == null) {
        instance = new ToastExample();
    }
    return instance;
}
public void setContext(Context context) { // This is also working fine
    Log.e(TAG, "setContext called");
    this.context = context;
}
public void showMessage(String message) { // I can able to see toast
    Toast.makeText(this.context, message, Toast.LENGTH_SHORT).show();
}

public void connectXMPP(String host, int port, String userName, String passWord) {
    Log.e(TAG, "_connectXMPP called");
    XMPPTCPConnectionConfiguration.Builder configBuilder = XMPPTCPConnectionConfiguration.builder(); // Here i got error
    configBuilder.setUsernameAndPassword(userName, passWord);
    ...............
    ...............
}

I am using below .Jar file in My Plugin and Unity

smack-core-4.1.4.jar
smack-extensions-4.1.4.jar
smack-im-4.1.4.jar
smack-android-4.1.4.jar
smack-android-extensions-4.1.4.jar
smack-tcp-4.1.4.jar
jxmpp-util-cache-0.4.2.jar
jxmpp-core-0.4.2.jar
jxmpp-jid-0.4.2.jar
jxmpp-stringprep-libidn-0.4.2.jar
minidns-core-0.2.0.jar**

Someone is also facing this issue but not found Check more

Please help me to sort out this issue, Thanks in Advance.!!!

Since nobody has answered here I how I solved it after 4 days R&D:

Please exrect all classes of Smack-core-4.1.1.jar file and past inside your app.
There is other 3 more file : version, smack-config.xml,jul.properties , Please paste this file in your Assests folder inside app.
In Smack packages there is one class : SmackInitialization.java, please replace below code. Code Here
Once you done please make .Jar file and use inside your Unity.Check Here

Let me know if you got same error i am happy to help you anytime for any solution.

Thanks