Swagger show hint for conditionally required nullable field

Question

I need to show in Swagger "nullable: true" where one field of request body is nullable and required conditionally.

I've tried following annotation. but doesn't help

[RequiredIfAttribute( "IdentificationType", IdentificationType.GROUP_MEMBER )]
[JsonProperty( Required = Required.AllowNull )]
public Title? PassengerTitle

Title is enum, RequiredIfAttribute is custom attribute.

I also tried to create SchemaFilter based on ISchemaFilter also don't know where to add get the hint there

Hier is a sample screen what I mean