It is impossible to change a default value of the ChoicesRestful.path…

src/base.ts

@@ -471,7 +471,7 @@ export class Base {
     if (this.isPropertyEmpty(res)) {
       const locStr = this.localizableStrings ? this.localizableStrings[name] : undefined;
       if(locStr) return locStr.text;
-      if (defaultValue != null) return defaultValue;
+      if (defaultValue !== null && defaultValue !== undefined) return defaultValue;
       const propDefaultValue = this.getDefaultPropertyValue(name);
       if(propDefaultValue !== undefined) return propDefaultValue;
     }

src/choicesRestful.ts

@@ -376,7 +376,8 @@ export class ChoicesRestful extends Base {
    */
 
   public get path(): string {
-    return this.getPropertyValue("path", "");
+    const res = this.getPropertyValue("path");
+    return !!res ? res : "";
   }
   public set path(val: string) {
     this.setPropertyValue("path", val);

tests/question_baseselecttests.ts

@@ -1189,4 +1189,11 @@ QUnit.test("Use carryForward with panel dynamic + update data on survey.data=dat
   assert.equal(q2.visibleChoices[1].value, 2, "the second value is correct");
   assert.equal(q2.visibleChoices[1].text, "Item 2", "the second text is correct");
 });
+QUnit.test("Allow to override default value fro choicesByUrl.path Bug#6766", function (assert) {
+  const prop = Serializer.findProperty("choicesByUrl", "path");
+  prop.defaultValue = "list";
+  const q1 = new QuestionDropdownModel("q1");
+  assert.equal(q1.choicesByUrl.path, "list", "get new default value for path");
+  prop.defaultValue = undefined;
+});