As defined by the IANA, the 204 status code means no content needs to be sent by the server.

Noncompliant Code Example (OpenAPI v2)

/pets/{petId}:
  delete:
    responses:
      '204':       # Noncompliant: 204 No Content MUST NOT return anything.
        description: delete pet
        schema:
          type: object

Compliant Solution

/pets/{petId}:
  delete:
    responses:
      '204':
        description: delete pet