[schema][algorithm][v3] Corrected definition of loop entry

Now the request and answer fields are properly defined.

beat/core/schema/algorithm/3.json

@@ -12,6 +12,22 @@
 
   "definitions": {
 
+    "loop_io_group": {
+      "type": "object",
+
+      "properties": {
+        "request": { "$ref": "common.json#/definitions/endpoint" },
+        "answer": { "$ref": "common.json#/definitions/endpoint" }
+      },
+
+      "required": [
+        "request",
+        "answer"
+      ],
+
+      "additionalProperties": false
+    },
+
     "loop_user_io_group": {
 
       "type": "object",
@@ -20,7 +36,7 @@
         "name": { "type": "string" },
         "inputs": { "$ref": "common.json#/definitions/endpoints" },
         "outputs": { "$ref": "common.json#/definitions/endpoints" },
-        "loop": { "$ref": "common.json#/definitions/endpoints" }
+        "loop": { "$ref": "#/definitions/loop_io_group" }
       },
 
       "required": [
@@ -55,7 +71,7 @@
       "properties": {
         "name": { "type": "string" },
         "inputs": { "$ref": "common.json#/definitions/endpoints" },
-        "loop": { "$ref": "common.json#/definitions/endpoints" }
+        "loop": { "$ref": "#/definitions/loop_io_group" }
       },
 
       "required": [