Program: 53204
Project: 53204
Buggy source:
public ActionWorkItemPopup(final Path path,final GuidedDecisionTable52 model,final IBindingProvider bindingProvider,final GenericColumnCommand refreshGrid,final ActionWorkItemCol52 col,final Set<PortableWorkDefinition> workItemDefinitions,final boolean isNew,final boolean isReadOnly){
  this.editingCol=cloneActionWorkItemColumn(col);
  this.path=path;
  this.model=model;
  this.isReadOnly=isReadOnly;
  this.workItemInputParameters=new WorkItemParametersWidget(bindingProvider,isReadOnly);
  setTitle(GuidedDecisionTableConstants.INSTANCE.ColumnConfigurationWorkItem());
  setModal(false);
  final TextBox header=new TextBox();
  header.setText(col.getHeader());
  header.setEnabled(!isReadOnly);
  if (!isReadOnly) {
    header.addChangeHandler(new ChangeHandler(){
      public void onChange(      ChangeEvent event){
        editingCol.setHeader(header.getText());
      }
    }
);
  }
  addAttribute(GuidedDecisionTableConstants.INSTANCE.ColumnHeaderDescription(),header);
  final ListBox workItemsListBox=new ListBox();
  addAttribute(GuidedDecisionTableConstants.INSTANCE.WorkItemNameColon(),workItemsListBox);
  workItemsListBox.setEnabled(!isReadOnly);
  if (!isReadOnly) {
    workItemsListBox.addChangeHandler(new ChangeHandler(){
      public void onChange(      ChangeEvent event){
        int index=workItemsListBox.getSelectedIndex();
        if (index >= 0) {
          String selectedWorkItemName=workItemsListBox.getValue(index);
          editingCol.setWorkItemDefinition(workItemDefinitionsMap.get(selectedWorkItemName));
          showWorkItemParameters();
          center();
        }
      }
    }
);
  }
  workItemInputParametersIndex=addAttribute(GuidedDecisionTableConstants.INSTANCE.WorkItemInputParameters(),workItemInputParameters,false);
  setupWorkItems(workItemsListBox,workItemDefinitions);
  addAttribute(new StringBuilder(GuidedDecisionTableConstants.INSTANCE.HideThisColumn()).append(GuidedDecisionTableConstants.COLON).toString(),DTCellValueWidgetFactory.getHideColumnIndicator(editingCol));
  Button apply=new Button(GuidedDecisionTableConstants.INSTANCE.ApplyChanges());
  apply.addClickHandler(new ClickHandler(){
    public void onClick(    ClickEvent w){
      if (null == editingCol.getHeader() || "String_Node_Str".equals(editingCol.getHeader())) {
        Window.alert(GuidedDecisionTableConstants.INSTANCE.YouMustEnterAColumnHeaderValueDescription());
        return;
      }
      if (isNew) {
        if (!unique(editingCol.getHeader())) {
          Window.alert(GuidedDecisionTableConstants.INSTANCE.ThatColumnNameIsAlreadyInUsePleasePickAnother());
          return;
        }
      }
 else {
        if (!col.getHeader().equals(editingCol.getHeader())) {
          if (!unique(editingCol.getHeader())) {
            Window.alert(GuidedDecisionTableConstants.INSTANCE.ThatColumnNameIsAlreadyInUsePleasePickAnother());
            return;
          }
        }
      }
      refreshGrid.execute(editingCol);
      hide();
    }
  }
);
  addAttribute("String_Node_Str",apply);
}

Fixed version (ground truth):
public ActionWorkItemPopup(final Path path,final GuidedDecisionTable52 model,final IBindingProvider bindingProvider,final GenericColumnCommand refreshGrid,final ActionWorkItemCol52 col,final Set<PortableWorkDefinition> workItemDefinitions,final boolean isNew,final boolean isReadOnly){
  this.editingCol=cloneActionWorkItemColumn(col);
  this.model=model;
  this.isReadOnly=isReadOnly;
  this.workItemInputParameters=new WorkItemParametersWidget(bindingProvider,isReadOnly);
  setTitle(GuidedDecisionTableConstants.INSTANCE.ColumnConfigurationWorkItem());
  setModal(false);
  final TextBox header=new TextBox();
  header.setText(col.getHeader());
  header.setEnabled(!isReadOnly);
  if (!isReadOnly) {
    header.addChangeHandler(new ChangeHandler(){
      public void onChange(      ChangeEvent event){
        editingCol.setHeader(header.getText());
      }
    }
);
  }
  addAttribute(GuidedDecisionTableConstants.INSTANCE.ColumnHeaderDescription(),header);
  final ListBox workItemsListBox=new ListBox();
  addAttribute(GuidedDecisionTableConstants.INSTANCE.WorkItemNameColon(),workItemsListBox);
  workItemsListBox.setEnabled(!isReadOnly);
  if (!isReadOnly) {
    workItemsListBox.addChangeHandler(new ChangeHandler(){
      public void onChange(      ChangeEvent event){
        int index=workItemsListBox.getSelectedIndex();
        if (index >= 0) {
          String selectedWorkItemName=workItemsListBox.getValue(index);
          editingCol.setWorkItemDefinition(workItemDefinitionsMap.get(selectedWorkItemName));
          showWorkItemParameters();
          center();
        }
      }
    }
);
  }
  workItemInputParametersIndex=addAttribute(GuidedDecisionTableConstants.INSTANCE.WorkItemInputParameters(),workItemInputParameters,false);
  setupWorkItems(workItemsListBox,workItemDefinitions);
  addAttribute(new StringBuilder(GuidedDecisionTableConstants.INSTANCE.HideThisColumn()).append(GuidedDecisionTableConstants.COLON).toString(),DTCellValueWidgetFactory.getHideColumnIndicator(editingCol));
  Button apply=new Button(GuidedDecisionTableConstants.INSTANCE.ApplyChanges());
  apply.addClickHandler(new ClickHandler(){
    public void onClick(    ClickEvent w){
      if (null == editingCol.getHeader() || "String_Node_Str".equals(editingCol.getHeader())) {
        Window.alert(GuidedDecisionTableConstants.INSTANCE.YouMustEnterAColumnHeaderValueDescription());
        return;
      }
      if (isNew) {
        if (!unique(editingCol.getHeader())) {
          Window.alert(GuidedDecisionTableConstants.INSTANCE.ThatColumnNameIsAlreadyInUsePleasePickAnother());
          return;
        }
      }
 else {
        if (!col.getHeader().equals(editingCol.getHeader())) {
          if (!unique(editingCol.getHeader())) {
            Window.alert(GuidedDecisionTableConstants.INSTANCE.ThatColumnNameIsAlreadyInUsePleasePickAnother());
            return;
          }
        }
      }
      refreshGrid.execute(editingCol);
      hide();
    }
  }
);
  addAttribute("String_Node_Str",apply);
}