Prompt for params

How does the prompt for parameters get called for Image?

Image.attachCommand("insertImage", type => ({
  label: "Insert image",
  run(pm, src, alt, title) {
    return{src, title, alt})).apply(andScroll)
  params: [
    {name: "Image URL", type: "text"},
    {name: "Description / alternative text", type: "text", default: ""},
    {name: "Title", type: "text", default: ""}
  select(pm) {
    return pm.doc.path(pm.selection.from.path).type.canContainType(type)
  menuGroup: "inline",
  menuRank: 40,
  prefillParams(pm) {
    let {node} = pm.selection
    if (node && node.type == type)
      return [node.attrs.src, node.attrs.alt, node.attrs.title]

Modules can register themselves as parameter handlers, and the src/menu/menu module does so. When multiple such modules did, you can use the commandParamHandler option. If you didn’t explicitly choose one, the default one from the menu module gets chosen.