FormBuilderMultiDropdown is a library that creates a Dropdown that allows the user to select one or more options from a dropdown menu. It complies with the FormBuilder library standards.

https://pub.dev/packages/flutter_form_builder

The source code of FormBuilderMultiDropdown is a modification of multi_dropdown 3.0.1+

https://pub.dev/packages/multi_dropdown

Usage:

// <ID, ITEM> = <String, String>
FormBuilderMultiDropdown<String, String> (
  name: "language",
  items: ["Java", "Javascript", "Swift"],
  initialValue: ["Java", "Swift"],
  validator: FormBuilderValidators.compose(
    [
      FormBuilderValidators.required(),
    ],
  ),
  getItemId: (String item)  {
     return item;
  },
  getItemText: (String item)  {
     return item;
  }
)