Program: 13894
Project: 13894
Buggy source:
private void showGroupNotificationForBuilder(Context context,NotificationCompat.Builder builder,String wpcomNoteID,String message,boolean notifyUser){
  if (builder == null || context == null) {
    return;
  }
  Bundle authPNBundle=sActiveNotificationsMap.remove(AUTH_PUSH_NOTIFICATION_ID);
  if (sActiveNotificationsMap.size() > 1) {
    NotificationCompat.InboxStyle inboxStyle=new NotificationCompat.InboxStyle();
    int noteCtr=1;
    for (    Bundle pushBundle : sActiveNotificationsMap.values()) {
      if (noteCtr > MAX_INBOX_ITEMS) {
        break;
      }
      if (pushBundle == null || pushBundle.getString(PUSH_ARG_MSG) == null) {
        continue;
      }
      if (pushBundle.getString(PUSH_ARG_TYPE,"String_Node_Str").equals(PUSH_TYPE_COMMENT)) {
        String pnTitle=StringEscapeUtils.unescapeHtml((pushBundle.getString(PUSH_ARG_TITLE)));
        String pnMessage=StringEscapeUtils.unescapeHtml((pushBundle.getString(PUSH_ARG_MSG)));
        inboxStyle.addLine(pnTitle + "String_Node_Str" + pnMessage);
      }
 else {
        String pnMessage=StringEscapeUtils.unescapeHtml((pushBundle.getString(PUSH_ARG_MSG)));
        inboxStyle.addLine(pnMessage);
      }
      noteCtr++;
    }
    if (sActiveNotificationsMap.size() > MAX_INBOX_ITEMS) {
      inboxStyle.setSummaryText(String.format(context.getString(R.string.more_notifications),sActiveNotificationsMap.size() - MAX_INBOX_ITEMS));
    }
    String subject=String.format(context.getString(R.string.new_notifications),sActiveNotificationsMap.size());
    NotificationCompat.Builder groupBuilder=new NotificationCompat.Builder(context).setSmallIcon(R.drawable.ic_my_sites_white_24dp).setColor(context.getResources().getColor(R.color.blue_wordpress)).setGroup(NOTIFICATION_GROUP_KEY).setGroupSummary(true).setAutoCancel(true).setTicker(message).setContentTitle(context.getString(R.string.app_name)).setContentText(subject).setStyle(inboxStyle);
    showNotificationForBuilder(groupBuilder,context,wpcomNoteID,GROUP_NOTIFICATION_ID,notifyUser);
  }
 else {
    builder.setGroupSummary(true);
    showNotificationForBuilder(builder,context,wpcomNoteID,GROUP_NOTIFICATION_ID,notifyUser);
  }
  if (authPNBundle != null) {
    sActiveNotificationsMap.put(AUTH_PUSH_NOTIFICATION_ID,authPNBundle);
  }
}

Fixed version (ground truth):
private void showGroupNotificationForBuilder(Context context,NotificationCompat.Builder builder,String wpcomNoteID,String message,boolean notifyUser){
  if (builder == null || context == null) {
    return;
  }
  Bundle authPNBundle=sActiveNotificationsMap.remove(AUTH_PUSH_NOTIFICATION_ID);
  if (sActiveNotificationsMap.size() > 1) {
    NotificationCompat.InboxStyle inboxStyle=new NotificationCompat.InboxStyle();
    int noteCtr=1;
    for (    Bundle pushBundle : sActiveNotificationsMap.values()) {
      if (noteCtr > MAX_INBOX_ITEMS) {
        break;
      }
      if (pushBundle == null || pushBundle.getString(PUSH_ARG_MSG) == null) {
        continue;
      }
      if (pushBundle.getString(PUSH_ARG_TYPE,"String_Node_Str").equals(PUSH_TYPE_COMMENT)) {
        String pnTitle=StringEscapeUtils.unescapeHtml4((pushBundle.getString(PUSH_ARG_TITLE)));
        String pnMessage=StringEscapeUtils.unescapeHtml4((pushBundle.getString(PUSH_ARG_MSG)));
        inboxStyle.addLine(pnTitle + "String_Node_Str" + pnMessage);
      }
 else {
        String pnMessage=StringEscapeUtils.unescapeHtml4((pushBundle.getString(PUSH_ARG_MSG)));
        inboxStyle.addLine(pnMessage);
      }
      noteCtr++;
    }
    if (sActiveNotificationsMap.size() > MAX_INBOX_ITEMS) {
      inboxStyle.setSummaryText(String.format(context.getString(R.string.more_notifications),sActiveNotificationsMap.size() - MAX_INBOX_ITEMS));
    }
    String subject=String.format(context.getString(R.string.new_notifications),sActiveNotificationsMap.size());
    NotificationCompat.Builder groupBuilder=new NotificationCompat.Builder(context).setSmallIcon(R.drawable.ic_my_sites_white_24dp).setColor(context.getResources().getColor(R.color.blue_wordpress)).setGroup(NOTIFICATION_GROUP_KEY).setGroupSummary(true).setAutoCancel(true).setTicker(message).setContentTitle(context.getString(R.string.app_name)).setContentText(subject).setStyle(inboxStyle);
    showNotificationForBuilder(groupBuilder,context,wpcomNoteID,GROUP_NOTIFICATION_ID,notifyUser);
  }
 else {
    builder.setGroupSummary(true);
    showNotificationForBuilder(builder,context,wpcomNoteID,GROUP_NOTIFICATION_ID,notifyUser);
  }
  if (authPNBundle != null) {
    sActiveNotificationsMap.put(AUTH_PUSH_NOTIFICATION_ID,authPNBundle);
  }
}