The label of a dedicated insert macro toolbar menu entry is ignored

// Declare a new toolbar item for the Floating box Table of Contents.
config.toolbarMenuItems.floatingBoxToc = {
  command: 'xwiki-macro-insert',
  label: 'Floating Table of Contents',
  data: {
    name: 'box',
    content: '{{toc/}}',
    parameters: {cssClass : "floatinginfobox", title : "Table of Contents"}
  }
};

// Modify the insert configuration to remove the code macro and to replace the default table of contents macro with the one in a floating box.
config.toolbarMenus.insert.groups[1] = {id: 'macros', items: ['infoBox', 'successBox', 'warningBox', 'errorBox', 'floatingBoxToc', 'include']};