code: protected void installDefaults() {
          updateStyle(splitPane);
  
          setOrientation(splitPane.getOrientation());
          setContinuousLayout(splitPane.isContinuousLayout());
  
          resetLayoutManager();
  
          /*
           * Install the nonContinuousLayoutDivider here to avoid having to
           * add/remove everything later.
           */
          if (nonContinuousLayoutDivider == null) {
              setNonContinuousLayoutDivider(createDefaultNonContinuousLayoutDivider(), true);
          } else {
              setNonContinuousLayoutDivider(nonContinuousLayoutDivider, true);
          }
  
          // focus forward traversal key
          if (managingFocusForwardTraversalKeys == null) {
              managingFocusForwardTraversalKeys = new HashSet();
              managingFocusForwardTraversalKeys.add(KeyStroke.getKeyStroke(KeyEvent.VK_TAB, 0));
          }
          splitPane.setFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, managingFocusForwardTraversalKeys);
          // focus backward traversal key
          if (managingFocusBackwardTraversalKeys == null) {
              managingFocusBackwardTraversalKeys = new HashSet();
              managingFocusBackwardTraversalKeys.add(KeyStroke.getKeyStroke(KeyEvent.VK_TAB, InputEvent.SHIFT_MASK));
          }
          splitPane.setFocusTraversalKeys(KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, managingFocusBackwardTraversalKeys);
      }
docs: Installs the UI defaults.