Program: 103468
Project: 103468
Buggy source:
/** 
 * Calls the given treeNode.
 * @param treeNode the <tt>TreeNode</tt> to call
 */
private void call(TreeNode treeNode){
  List<UIContactDetail> telephonyContacts=((ContactNode)treeNode).getContactDescriptor().getContactDetailsForOperationSet(OperationSetBasicTelephony.class);
  ChooseCallAccountPopupMenu chooseAccountDialog=null;
  if (telephonyContacts.size() == 1) {
    UIContactDetail detail=telephonyContacts.get(0);
    ProtocolProviderService preferredProvider=detail.getPreferredProtocolProvider(OperationSetBasicTelephony.class);
    List<ProtocolProviderService> providers=null;
    String protocolName=null;
    if (preferredProvider != null) {
      if (preferredProvider.isRegistered())       CallManager.createCall(preferredProvider,detail.getAddress());
 else {
        protocolName=preferredProvider.getProtocolName();
        providers=CallManager.getRegisteredProviders(protocolName,OperationSetBasicTelephony.class);
      }
    }
 else {
      protocolName=detail.getPreferredProtocol(OperationSetBasicTelephony.class);
      providers=CallManager.getRegisteredProviders(protocolName,OperationSetBasicTelephony.class);
    }
    if (providers != null) {
      int providersCount=providers.size();
      if (providersCount <= 0) {
        new ErrorDialog(null,GuiActivator.getResources().getI18NString("String_Node_Str"),GuiActivator.getResources().getI18NString("String_Node_Str",new String[]{protocolName})).showDialog();
      }
 else       if (providersCount == 1) {
        CallManager.createCall(providers.get(0),detail.getAddress());
      }
 else       if (providersCount > 1)       chooseAccountDialog=new ChooseCallAccountPopupMenu(tree,detail.getAddress(),providers);
    }
  }
 else   if (telephonyContacts.size() > 1) {
    chooseAccountDialog=new ChooseCallAccountPopupMenu(tree,telephonyContacts);
  }
  if (chooseAccountDialog != null) {
    Point location=new Point(callButton.getX(),callButton.getY() + callButton.getHeight());
    SwingUtilities.convertPointToScreen(location,tree);
    location.y=location.y + tree.getPathBounds(tree.getSelectionPath()).y;
    chooseAccountDialog.showPopupMenu(location.x + 8,location.y - 8);
  }
}

Fixed version (ground truth):
/** 
 * Calls the given treeNode.
 * @param treeNode the <tt>TreeNode</tt> to call
 */
private void call(TreeNode treeNode){
  List<UIContactDetail> telephonyContacts=((ContactNode)treeNode).getContactDescriptor().getContactDetailsForOperationSet(OperationSetBasicTelephony.class);
  ChooseCallAccountPopupMenu chooseAccountDialog=null;
  if (telephonyContacts.size() == 1) {
    UIContactDetail detail=telephonyContacts.get(0);
    ProtocolProviderService preferredProvider=detail.getPreferredProtocolProvider(OperationSetBasicTelephony.class);
    List<ProtocolProviderService> providers=null;
    String protocolName=null;
    if (preferredProvider != null) {
      if (preferredProvider.isRegistered())       CallManager.createCall(preferredProvider,detail.getAddress());
 else {
        protocolName=preferredProvider.getProtocolName();
        providers=GuiActivator.getRegisteredProviders(protocolName,OperationSetBasicTelephony.class);
      }
    }
 else {
      protocolName=detail.getPreferredProtocol(OperationSetBasicTelephony.class);
      if (protocolName != null)       providers=GuiActivator.getRegisteredProviders(protocolName,OperationSetBasicTelephony.class);
 else       providers=CallManager.getTelephonyProviders();
    }
    if (providers != null) {
      int providersCount=providers.size();
      if (providersCount <= 0) {
        new ErrorDialog(null,GuiActivator.getResources().getI18NString("String_Node_Str"),GuiActivator.getResources().getI18NString("String_Node_Str",new String[]{protocolName})).showDialog();
      }
 else       if (providersCount == 1) {
        CallManager.createCall(providers.get(0),detail.getAddress());
      }
 else       if (providersCount > 1)       chooseAccountDialog=new ChooseCallAccountPopupMenu(tree,detail.getAddress(),providers);
    }
  }
 else   if (telephonyContacts.size() > 1) {
    chooseAccountDialog=new ChooseCallAccountPopupMenu(tree,telephonyContacts);
  }
  if (chooseAccountDialog != null) {
    Point location=new Point(callButton.getX(),callButton.getY() + callButton.getHeight());
    SwingUtilities.convertPointToScreen(location,tree);
    location.y=location.y + tree.getPathBounds(tree.getSelectionPath()).y;
    chooseAccountDialog.showPopupMenu(location.x + 8,location.y - 8);
  }
}