fix: mapped types shim should return classes #2610

Author: kamilmysliwiec

lib/extra/swagger-shim.ts

@@ -153,16 +153,16 @@ export function SwaggerModule() {
   return () => {};
 }
 export function IntersectionType() {
-  return () => {};
+  return class {};
 }
 export function OmitType() {
-  return () => {};
+  return class {};
 }
 export function PartialType() {
-  return () => {};
+  return class {};
 }
 export function PickType() {
-  return () => {};
+  return class {};
 }
 export function getSchemaPath() {
   return () => '';