AIButton fails to initialize after following instructions in Integration.md

[nshdesai]

E/AndroidRuntime: FATAL EXCEPTION: main
                  Process: com.wordwrite.nsh.wordwrite, PID: 10873
                  java.lang.RuntimeException: Unable to start activity ComponentInfo{com.wordwrite.nsh.wordwrite/com.wordwrite.nsh.wordwrite.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void ai.api.ui.AIButton.initialize(ai.api.android.AIConfiguration)' on a null object reference
                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2946)
                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3046)
                      at android.app.ActivityThread.-wrap11(Unknown Source:0)
                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1688)
                      at android.os.Handler.dispatchMessage(Handler.java:105)
                      at android.os.Looper.loop(Looper.java:164)
                      at android.app.ActivityThread.main(ActivityThread.java:6798)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
                   Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void ai.api.ui.AIButton.initialize(ai.api.android.AIConfiguration)' on a null object reference
                      at com.wordwrite.nsh.wordwrite.MainActivity.onCreate(MainActivity.java:30)
                      at android.app.Activity.performCreate(Activity.java:7003)
                      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1230)
                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2899)
                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3046) 
                      at android.app.ActivityThread.-wrap11(Unknown Source:0) 
                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1688) 
                      at android.os.Handler.dispatchMessage(Handler.java:105) 
                      at android.os.Looper.loop(Looper.java:164) 
                      at android.app.ActivityThread.main(ActivityThread.java:6798) 
                      at java.lang.reflect.Method.invoke(Native Method) 
                      at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767) 

Above are the log files from the project.
Let me know of any possible solutions. Thanks!