Program: 189182
Project: 189182
Buggy source:
public void layout(){
  super.layout();
  if (getProject().equals(StoredProject.getDefault())) {
    requirePermission(new ProjectListPermission());
  }
  add(CSSPackageResource.getHeaderContribution(getClass(),"String_Node_Str"));
  final MilestoneFilterPanel filter=new MilestoneFilterPanel("String_Node_Str",getSession().getUser());
  add(filter);
  hideProject=!getProject().equals(StoredProject.getDefault());
  SortableEntityProvider<MilestoneGroup> provider=new MilestoneGroupProvider(getProject(),filter);
  List<MilestoneGroup> groups=MilestonesApplication.getMilestoneGroups(getProject(),filter);
  hasGroups=groups.size() > 0;
  add(new StripedDataView<MilestoneGroup>("String_Node_Str",provider){
    @Override protected void populateItem(    Item<MilestoneGroup> item){
      MilestoneGroup group=item.getModelObject();
      PageParameters params=new PageParameters();
      params.add("String_Node_Str",group.getProject().getId());
      params.add("String_Node_Str",group.getName());
      BookmarkablePageLink nameLink=new BookmarkablePageLink("String_Node_Str",getPageClass("String_Node_Str"),params);
      nameLink.add(new Label("String_Node_Str",group.getName()));
      item.add(nameLink);
      double part=group.getCompleteness();
      int percent=(int)(part * 100);
      Panel panel=new PercentagePanel("String_Node_Str",percent);
      item.add(panel);
      SortableEntityProvider<Milestone> provider=new GroupedMilestoneProvider(group,filter);
      item.add(new MilestoneListPanel("String_Node_Str",provider,Milestones.this,hideProject));
    }
  }
);
  if (getProject().equals(StoredProject.getDefault())) {
    ungroupedProvider=new GroupedMilestoneProvider(null,filter);
  }
 else {
    ungroupedProvider=new GroupedMilestoneProvider(null,getProject(),filter);
  }
  add(ungrouped=new WebMarkupContainer("String_Node_Str"));
  ungrouped.setOutputMarkupPlaceholderTag(true);
  add(ungroupedMilestones=new MilestoneListPanel("String_Node_Str",ungroupedProvider,this,hideProject));
  ungroupedMilestones.setOutputMarkupPlaceholderTag(true);
}

Fixed version (ground truth):
public void layout(){
  super.layout();
  if (getProject().equals(StoredProject.getDefault())) {
    requirePermission(new ProjectListPermission());
  }
  add(CSSPackageResource.getHeaderContribution(getClass(),"String_Node_Str"));
  final MilestoneFilterPanel filter=new MilestoneFilterPanel("String_Node_Str",getSession().getUser());
  add(filter);
  hideProject=!getProject().equals(StoredProject.getDefault());
  SortableEntityProvider<MilestoneGroup> provider=new MilestoneGroupProvider(getProject(),filter);
  List<MilestoneGroup> groups=MilestonesApplication.getMilestoneGroups(getProject(),filter);
  hasGroups=groups.size() > 0;
  add(new StripedDataView<MilestoneGroup>("String_Node_Str",provider){
    @Override protected void populateItem(    Item<MilestoneGroup> item){
      MilestoneGroup group=item.getModelObject();
      PageParameters params=new PageParameters();
      params.add("String_Node_Str",group.getProject().getId());
      params.add("String_Node_Str",group.getName());
      BookmarkablePageLink nameLink=new BookmarkablePageLink("String_Node_Str",getPageClass("String_Node_Str"),params);
      nameLink.add(new Label("String_Node_Str",group.getName()));
      item.add(nameLink);
      double part=group.getCompleteness();
      int percent=(int)(part * 100);
      Panel panel=new PercentagePanel("String_Node_Str",percent);
      item.add(panel);
      SortableEntityProvider<Milestone> provider=new GroupedMilestoneProvider(group,filter);
      item.add(new MilestoneListPanel("String_Node_Str",provider,Milestones.this,hideProject,group));
    }
  }
);
  if (getProject().equals(StoredProject.getDefault())) {
    ungroupedProvider=new GroupedMilestoneProvider(null,filter);
  }
 else {
    ungroupedProvider=new GroupedMilestoneProvider(null,getProject(),filter);
  }
  add(ungrouped=new WebMarkupContainer("String_Node_Str"));
  ungrouped.setOutputMarkupPlaceholderTag(true);
  add(ungroupedMilestones=new MilestoneListPanel("String_Node_Str",ungroupedProvider,this,hideProject,null));
  ungroupedMilestones.setOutputMarkupPlaceholderTag(true);
}