2 levels navigation using Slices

2-levels-nav.json

{
  "Menu" : {
    "uid" : {
      "type" : "UID",
      "config" : {
        "placeholder" : "unique-menu-id"
      }
    },
    "body" : {
      "fieldset" : "Navigation",
      "type" : "Slices",
      "config" : {
        "choices" : {
          "2levels-nav" : {
            "type" : "Slice",
            "non-repeat" : {
              "text" : {
                "type" : "StructuredText",
                "fieldset" : "Text",
                "config" : {
                  "single" : "heading2",
                  "placeholder" : "Country"
                }
              },
              "link" : {
                "type" : "Link",
                "fieldset" : "Target link",
                "config" : {
                  "select" : "document",
                  "masks" : [ "country" ],
                  "placeholder" : "Select a country"
                }
              }
            },
            "repeat" : {
              "text" : {
                "type" : "StructuredText",
                "fieldset" : "Text",
                "config" : {
                  "single" : "heading3",
                  "placeholder" : "Link label"
                }
              },
              "link" : {
                "type" : "Link",
                "fieldset" : "Region page",
                "config" : {
                  "select" : "document",
                  "masks" : [ "region" ],
                  "placeholder" : "Select a region page"
                }
              }
            }
          }
        }
      }
    }
  }
}