Changes to Checks whether a user with the given email exists in the system

the status response's property type changed from integer to string, and format from int32 to no format for status 200

removed the optional property error from the response with the 200 status

removed the optional property message from the response with the 200 status

removed the optional property path from the response with the 200 status

removed the optional property timestamp from the response with the 200 status

added the non-success response with the status 400

added the non-success response with the status 403

added the optional property body to the response with the 200 status

added the optional property header to the response with the 200 status

added the optional property id to the response with the 200 status