feat: support array within array in 3.x

lib/list.js

@@ -64,7 +64,12 @@ function List(items, itemType, parent) {
   }
 
   List.prototype.toItem = function(item) {
-    return isClass(this.itemType) ? new this.itemType(item) : this.itemType(item);
+    if (isClass(this.itemType)) {
+      return new this.itemType(item);
+    } else {
+      if (Array.isArray(item)) return item;
+      else return this.itemType(item);
+    }
   };
 
   items.forEach(function(item, i) {
@@ -91,7 +96,10 @@ List.prototype.push = function(obj) {
 List.prototype.toObject = function(onlySchema, removeHidden, removeProtected) {
   const items = [];
   this.forEach(function(item) {
-    if (item && typeof item === 'object' && item.toObject) {
+    if (item && Array.isArray(item) && item.toArray) {
+      const subArray = item.toArray();
+      items.push(subArray);
+    } else if (item && typeof item === 'object' && item.toObject) {
       items.push(item.toObject(onlySchema, removeHidden, removeProtected));
     } else {
       items.push(item);

test/introspection.test.js

@@ -27,6 +27,9 @@ const json = {
     {label: 'work', id: 'x@sample.com'},
     {label: 'home', id: 'x@home.com'},
   ],
+  nestedArray: [
+    [{msg: 'Hi'}],
+  ],
   tags: [],
 };