diff --git a/schema/common.json b/schema/common.json
index ece4bc439d39d8d009e41213a0e85e411ee3af1e..1e130c4ef3fd6f895aa6babfbd240d6587758063 100644
--- a/schema/common.json
+++ b/schema/common.json
@@ -15,6 +15,7 @@
         },
         {
           "type": "array",
+          "minItems": 1,
           "items": {
             "anyOf": [
               {