Use fix from develop; close #510

src/types/object.js

@@ -121,7 +121,9 @@ function objectType(value, path, resolve, traverseCallback) {
       if (requiredProperties.indexOf(key) !== -1) {
         props[key] = properties[key];
       }
-    } else if (properties[key]) {
+    }
+
+    if (properties[key]) {
       props[key] = properties[key];
     }