docs: public static BugCollection combineBugHistories() {
          try {
              FBFileChooser chooser = new FBFileChooser();
              chooser.setFileFilter(new FindBugsAnalysisFileFilter());
              // chooser.setCurrentDirectory(GUISaveState.getInstance().getStarterDirectoryForLoadBugs());
              // This is done by FBFileChooser.
              chooser.setMultiSelectionEnabled(true);
              chooser.setDialogTitle(edu.umd.cs.findbugs.L10N.getLocalString("dlg.choose_xmls_ttl", "Choose All XML's To Combine"));
              if (chooser.showOpenDialog(MainFrame.getInstance()) == JFileChooser.CANCEL_OPTION) {
                  return null;
              }
  
              SortedBugCollection conglomeration = new SortedBugCollection();
              conglomeration.readXML(chooser.getSelectedFiles()[0]);
              Update update = new Update();
              for (int x = 1; x < chooser.getSelectedFiles().length; x++) {
                  File f = chooser.getSelectedFiles()[x];
                  SortedBugCollection col = new SortedBugCollection();
                  col.readXML(f);
                  conglomeration = (SortedBugCollection) update.mergeCollections(conglomeration, col, false, false);// False
                  // means
                  // dont
                  // show
                  // dead
                  // bugs
              }
  
              return conglomeration;
          } catch (IOException e) {
              Debug.println(e);
              return null;
          } catch (DocumentException e) {
              Debug.println(e);
              return null;
          }
  
      }