text: from typing import Optional
  from requests import Response
  
  from schemathesis.models import Case
  from schemathesis.hooks import HookContext
  
  from . import get_request_header, original_case_successful, set_request_header
  
  
  def add_invalid_request_content_type(
      context: HookContext, case: Case, response: Response
  ) -> Optional[Case]:
      if original_case_successful(response):
          set_request_header(case, "Content-Type", "invalid/content/type")
          return case
      else:
          return None
  
  
  def invalid_request_content_type(response: Response, case: Case) -> Optional[bool]:
      if (
          response.request.body
          and get_request_header(response.request, "Content-Type") == "invalid/content/type"
      ):
          assert (
              response.status_code == 415
          ), "415 status code must be used when the client sends a payload with a content-type not supported by the server. https://cloud.ibm.com/docs/api-handbook?topic=api-handbook-headers#representation-headers"
      else:
          # skips the check when it's not relevant
          return True
      return None
  