20.9. Multipart FormData Output with java.util.Map

If the body parts are uniform, you can provide a java.util.Map as your input parameter and avoid unmarshaling each part manually or using a MultipartFormDataOutput object. As you can see in the example code below, this must include the type being unmarshaled with the generic parameter of the List type declaration. You must also annotate the method with @PartType to specify each part's media type. This example returns a customer list to a client, where each customer is a JAXB object.
   @Path("/multipart")
   public class MyService
   {
      @GET
      @Produces("multipart/form-data")
      @PartType("application/xml")
      public Map<String, Customer> get()
      {
         ...
      }
   }