static Type getResolvedType(Class<?> targetClass, @Nullable Object conversionHint) {
        if (conversionHint instanceof MethodParameter) {
            MethodParameter param = (MethodParameter) conversionHint;
            param = param.nestedIfOptional();
            if (Message.class.isAssignableFrom(param.getParameterType())) {
                param = param.nested();
            }
            Type genericParameterType = param.getNestedGenericParameterType();
            Class<?> contextClass = param.getContainingClass();
            return GenericTypeResolver.resolveType(genericParameterType, contextClass);
        }
        return targetClass;
    }
@param fastJsonConfig the fastJsonConfig to set.
extension-spring6/src/main/java/com/alibaba/fastjson2/support/spring6/messaging/converter/MappingFastJsonMessageConverter.java