Program: 39920
Project: 39920
Buggy source:
private void showNotification(){
  Intent phoneIntent=new Intent(this,HfpTestActivity.class);
  PendingIntent phonePIntent=PendingIntent.getActivity(this,1,phoneIntent,0);
  Intent acceptIntent=new Intent(this,HFPNotificationService.class);
  acceptIntent.setAction("String_Node_Str");
  PendingIntent acceptPIntent=PendingIntent.getService(this,0,acceptIntent,0);
  Intent rejectIntent=new Intent(this,HFPNotificationService.class);
  rejectIntent.setAction("String_Node_Str");
  PendingIntent rejectPIntent=PendingIntent.getService(this,0,rejectIntent,0);
  Intent hangupIntent=new Intent(this,HFPNotificationService.class);
  hangupIntent.setAction("String_Node_Str");
  hangupIntent.putExtra("String_Node_Str",callId);
  PendingIntent hangupPIntent=PendingIntent.getService(this,0,hangupIntent,0);
  Log.d(TAG,"String_Node_Str" + sigStrength);
  if (sigStrength > 4)   sigStrength=4;
  if (sigStrength < 0)   sigStrength=0;
  String signalIcon="String_Node_Str";
  if (!cellConnected)   signalIcon+="String_Node_Str";
 else {
    signalIcon+=Integer.toString(sigStrength);
    if (roaming)     signalIcon+="String_Node_Str";
 else     signalIcon+="String_Node_Str";
  }
  Notification.Builder builder=new Notification.Builder(this).setContentTitle("String_Node_Str").setContentText("String_Node_Str" + (connected ? 1 : 0) + "String_Node_Str"+ cellBattery+ "String_Node_Str"+ (audioConnected ? 1 : 0)).setSmallIcon(getResources().getIdentifier(signalIcon,"String_Node_Str",this.getPackageName())).setContentIntent(phonePIntent).setOngoing(true);
  if (ringing && !onCall) {
    builder.setContentTitle("String_Node_Str" + ringingNumber);
    builder.addAction(android.R.drawable.ic_media_play,"String_Node_Str",acceptPIntent);
    builder.addAction(android.R.drawable.ic_media_pause,"String_Node_Str",rejectPIntent);
    builder.setSound(RingtoneManager.getDefaultUri(RingtoneManager.TYPE_RINGTONE));
    builder.setPriority(Notification.PRIORITY_MAX);
  }
 else   if (ringing) {
    builder.addAction(android.R.drawable.ic_media_play,"String_Node_Str",acceptPIntent);
    builder.addAction(android.R.drawable.ic_media_pause,"String_Node_Str",rejectPIntent);
    builder.setPriority(Notification.PRIORITY_MAX);
    builder.setContentText("String_Node_Str" + ringingNumber);
  }
 else   if (onCall) {
    builder.addAction(android.R.drawable.ic_media_play,"String_Node_Str",hangupPIntent);
    builder.setContentText("String_Node_Str" + callNumber);
  }
  notification=builder.build();
  if (ringing)   notification.flags=Notification.FLAG_INSISTENT;
}

Fixed version (ground truth):
private void showNotification(){
  Intent phoneIntent=new Intent(this,HfpTestActivity.class);
  PendingIntent phonePIntent=PendingIntent.getActivity(this,1,phoneIntent,0);
  Intent acceptIntent=new Intent(this,HFPNotificationService.class);
  acceptIntent.setAction("String_Node_Str");
  PendingIntent acceptPIntent=PendingIntent.getService(this,0,acceptIntent,0);
  Intent rejectIntent=new Intent(this,HFPNotificationService.class);
  rejectIntent.setAction("String_Node_Str");
  PendingIntent rejectPIntent=PendingIntent.getService(this,0,rejectIntent,0);
  Intent hangupIntent=new Intent(this,HFPNotificationService.class);
  hangupIntent.setAction("String_Node_Str");
  hangupIntent.putExtra("String_Node_Str",callId);
  PendingIntent hangupPIntent=PendingIntent.getService(this,0,hangupIntent,0);
  Log.d(TAG,"String_Node_Str" + sigStrength);
  if (sigStrength > 4)   sigStrength=4;
  if (sigStrength < 0)   sigStrength=0;
  String signalIcon="String_Node_Str";
  if (!cellConnected)   signalIcon+="String_Node_Str";
 else {
    signalIcon+=Integer.toString(sigStrength);
    if (roaming)     signalIcon+="String_Node_Str";
 else     signalIcon+="String_Node_Str";
  }
  Notification.Builder builder=new Notification.Builder(this).setContentTitle("String_Node_Str").setContentText("String_Node_Str" + (connected ? 1 : 0) + "String_Node_Str"+ cellBattery+ "String_Node_Str"+ (audioConnected ? 1 : 0)).setSmallIcon(getResources().getIdentifier(signalIcon,"String_Node_Str",this.getPackageName())).setContentIntent(phonePIntent).setOngoing(true);
  if (ringing && !onCall && ringingHoldover < System.currentTimeMillis() + 15000) {
    builder.setContentTitle("String_Node_Str" + ringingNumber);
    builder.addAction(android.R.drawable.ic_media_play,"String_Node_Str",acceptPIntent);
    builder.addAction(android.R.drawable.ic_media_pause,"String_Node_Str",rejectPIntent);
    builder.setSound(RingtoneManager.getDefaultUri(RingtoneManager.TYPE_RINGTONE));
    builder.setPriority(Notification.PRIORITY_MAX);
  }
 else   if (ringing) {
    builder.addAction(android.R.drawable.ic_media_play,"String_Node_Str",acceptPIntent);
    builder.addAction(android.R.drawable.ic_media_pause,"String_Node_Str",rejectPIntent);
    builder.setPriority(Notification.PRIORITY_MAX);
    builder.setContentText("String_Node_Str" + ringingNumber);
  }
 else   if (onCall) {
    builder.addAction(android.R.drawable.ic_media_play,"String_Node_Str",hangupPIntent);
    builder.setContentText("String_Node_Str" + callNumber);
  }
  notification=builder.build();
  if (ringing)   notification.flags=Notification.FLAG_INSISTENT;
}