code: private void updateCurrentToolTipText() {
          String toolTipText;
          final boolean disabled = !isEnabled();
          final boolean selected = isSelected();
  
          if (disabled && selected && disabledSelectedToolTipText != null) {
              toolTipText = disabledSelectedToolTipText;
          } else if (disabled && disabledToolTipText != null) {
              toolTipText = disabledToolTipText;
          } else if (selected && selectedToolTipText != null) {
              toolTipText = selectedToolTipText;
          } else {
              toolTipText = defaultToolTipText;
          }
  
          super.setToolTipText(toolTipText);
      }
docs: Updates the current tool tip text based on the toggle button's state.
  <table>
  <caption>The tool tip that will be set based on button's state</caption>
  <tr>
  <td>State</td>
  <td>Tool tip text set</td>
  </tr>
  <tr>
  <td>Disabled and selected</td>
  <td>{@code disabledSelectedToolTipText} if non-{@code null} otherwise {@code defaultToolTipText}</td>
  </tr>
  <tr>
  <td>Disabled</td>
  <td>{@code disabledToolTipText} if non-{@code null} otherwise {@code defaultToolTipText}</td>
  </tr>
  <tr>
  <td>Selected (but not disabled)</td>
  <td>{@code selectedToolTipText} if non-{@code null} otherwise {@code defaultToolTipText}</td>
  </tr>
  <tr>
  <td>Other states</td>
  <td>{@code defaultToolTipText}</td>
  </tr>
  </table>
  
  @see #defaultToolTipText
  @see #selectedToolTipText
  @see #disabledToolTipText
  @see #disabledSelectedToolTipText