relationships are a list

src/locations/room.jsonnet

@@ -12,6 +12,8 @@ entity
   properties+: {
     location: types.location,
     relationships: {
+      type: 'array',
+      items: {
         type: 'object',
         description: 'Relationships that bind other entities to this room.',
         properties: {
@@ -23,4 +25,5 @@ entity
         },
       },
     },
+  },
 }