[BUG] [cpp-ue4] Missing WriteJsonValue and TryGetJsonValue for arbitrary-typed variables

[madrazzl3]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
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Description

This bug was brought in PR #10267, where type TSharedPtr<FJsonValue> was introduced to hold arbitrary-typed variables. However, this solution was not complete because it's missing overloads of WriteJsonValue and TryGetJsonValue functions for TSharedPtr<FJsonValue> type, that leads to compile-time errors.

openapi-generator version

master - 5.3.0

OpenAPI declaration file content or url

Full scheme

arrayOfSomething:
          type: array
          items: {}
          nullable: true

Generation Details

openapi-generator  generate -i https://gist.githubusercontent.com/madrazzl3/da2502b6816aaa98713cba75e595f373/raw/d53da8c6098167768c3e5b1ad1381467397d6a51/example-scheme.yaml -g cpp-ue4 -o generated-client/ --additional-properties=cppNamespace='api',unrealModuleName='MyAPI',modelNamePrefix=''

Steps to reproduce

1. Generate UE4 client with any of available tools
2. Try to build generated module

Related issues/PRs

Issue #10266

Suggest a fix

We need to define proper implementations of WriteJsonValue and TryGetJsonValue for TSharedPtr<FJsonValue> type used for arbitrary-typed variables.

inline void WriteJsonValue(JsonWriter& Writer, const TSharedPtr<FJsonValue>& Value)
{
	if (Value.IsValid())
	{
		FJsonSerializer::Serialize(Value.ToSharedRef(), "", Writer, false);
	}
	else
	{
		Writer->WriteObjectStart();
		Writer->WriteObjectEnd();
	}
}

inline bool TryGetJsonValue(const TSharedPtr<FJsonValue>& JsonValue, TSharedPtr<FJsonValue>& JsonObjectValue)
{
	JsonObjectValue = JsonValue;
	return true;
}