[go-server] Feat: add required assertions to models (#10068)

* Add RequiredError

* Add IsZeroValue helper

* Add AssertRequired method to all models

* Add AssertRequired call for body param

* Regenerate files

* Add DisallowUnknownFields

* Regenerate samples

* Use hasRequired in model to remove unnecessary code

* Revert disallowUnknownFields

* Use isAdditionalPropertiesTrue for disallowing unknown fields

* Updated samples

* Fix indent

* Add require checks for nested slices

* Add new tests

* Regenerate samples

* Regenerate samples after merging

samples/server/petstore/go-api-server/go/model_user.go

@@ -29,3 +29,20 @@ type User struct {
 	// User Status
 	UserStatus int32 `json:"userStatus,omitempty"`
 }
+
+// AssertUserRequired checks if the required fields are not zero-ed
+func AssertUserRequired(obj User) error {
+	return nil
+}
+
+// AssertRecurseUserRequired recursively checks if required fields are not zero-ed in a nested slice.
+// Accepts only nested slice of User (e.g. [][]User), otherwise ErrTypeAssertionError is thrown.
+func AssertRecurseUserRequired(objSlice interface{}) error {
+	return AssertRecurseInterfaceRequired(objSlice, func(obj interface{}) error {
+		aUser, ok := obj.(User)
+		if !ok {
+			return ErrTypeAssertionError
+		}
+		return AssertUserRequired(aUser)
+	})
+}