required field on response header spec not parsed correctly

The following response header YAML definition gives an error while generating C# Core 3.1 code:

  responses:
    '200':
      description: OK
      headers:
        Last-Modified:
          description: The UTC datetime at when the item was last modified
          required: true
          schema:
            type: string

Exception: Newtonsoft.Json.JsonSerializationException: Error converting value "true" to type 'System.Collections.Generic.ICollection1[System.String]'. Path 'paths['/item/{id}'].head.responses.200.headers.Last-Modified.required', line 1, position 2518. ---> System.ArgumentException: Could not cast or convert from System.String to System.Collections.Generic.ICollection1[System.String].

It looks like the generator is expecting a string array, while the required parameter should be parsed as a boolean, just like path parameters

(version 13.6.2)