normalizing common structures for propulsion and vehicle type

Author: thekaveman

schema/templates/common.json

@@ -73,21 +73,26 @@
       },
       "additionalProperties": false
     },
+    "propulsion_type": {
+      "$id": "#/definitions/propulsion_type",
+      "type": "string",
+      "description": "The type of propulsion",
+      "enum": [
+        "combustion",
+        "electric",
+        "electric_assist",
+        "human"
+      ]
+    },
     "propulsion_types": {
       "$id": "#/definitions/propulsion_types",
       "type": "array",
-      "description": "The type of propulsion; allows multiple values",
+      "description": "Array of propulsion types, allowing multiple values",
       "items": {
-        "type": "string",
-        "enum": [
-          "combustion",
-          "electric",
-          "electric_assist",
-          "human"
-        ]
+        "$id": "#/definitions/propulsion_types/items",
+        "$ref": "#/definitions/propulsion_type"
       },
-      "uniqueItems": true,
-      "minItems": 1
+      "uniqueItems": true
     },
     "rental_methods": {
       "$id": "#/definitions/rental_methods",
@@ -420,7 +425,8 @@
         "propulsion_types": {
           "$id": "#/definitions/vehicle/properties/propulsion_types",
           "$ref": "#/definitions/propulsion_types",
-          "description": "The type of propulsion; allows multiple values"
+          "description": "The type of propulsion; allows multiple values",
+          "minItems": 1
         }
       },
       "additionalProperties": false
@@ -632,6 +638,16 @@
         "other"
       ]
     },
+    "vehicle_types": {
+      "$id": "#/definitions/vehicle_types",
+      "type": "array",
+      "description": "Array of vehicle types",
+      "items": {
+        "$id": "#/definitions/vehicle_types/items",
+        "$ref": "#/definitions/vehicle_type"
+      },
+      "uniqueItems": true
+    },
     "version": {
       "$id": "#/definitions/version",
       "type": "string",