ant-design-vue/components/dropdown/index.js

import Dropdown from './dropdown'
import DropdownButton from './dropdown-button'

export { DropdownProps } from './dropdown'
export { DropdownButtonProps } from './dropdown-button'

Dropdown.Button = DropdownButton

/* istanbul ignore next */
Dropdown.install = function (Vue) {
  Vue.component(Dropdown.name, Dropdown)
  Vue.component(DropdownButton.name, DropdownButton)
}

export default Dropdown