code: @Override
    public void createPartControl(Composite parent) {
      Tree main =
          new Tree(parent, SWT.SINGLE | SWT.FULL_SELECTION | SWT.H_SCROLL
              | SWT.V_SCROLL);
      main.setHeaderVisible(true);
      main.setLinesVisible(false);
      main.setLayoutData(new GridData(GridData.FILL_BOTH));
  
      TreeColumn serverCol = new TreeColumn(main, SWT.SINGLE);
      serverCol.setText("Location");
      serverCol.setWidth(300);
      serverCol.setResizable(true);
  
      TreeColumn locationCol = new TreeColumn(main, SWT.SINGLE);
      locationCol.setText("Master node");
      locationCol.setWidth(185);
      locationCol.setResizable(true);
  
      TreeColumn stateCol = new TreeColumn(main, SWT.SINGLE);
      stateCol.setText("State");
      stateCol.setWidth(95);
      stateCol.setResizable(true);
  
      TreeColumn statusCol = new TreeColumn(main, SWT.SINGLE);
      statusCol.setText("Status");
      statusCol.setWidth(300);
      statusCol.setResizable(true);
  
      viewer = new TreeViewer(main);
      viewer.setContentProvider(this);
      viewer.setLabelProvider(this);
      viewer.setInput(CONTENT_ROOT); // don't care
  
      getViewSite().setSelectionProvider(viewer);
      
      getViewSite().getActionBars().setGlobalActionHandler(
          ActionFactory.DELETE.getId(), deleteAction);
      getViewSite().getActionBars().getToolBarManager().add(editServerAction);
      getViewSite().getActionBars().getToolBarManager().add(newLocationAction);
  
      createActions();
      createContextMenu();
    }
docs: Creates the columns for the view