HTTP 100 - Continue
Information about HTTP status code 100, its meaning, and any related restrictions.
Indicates that request headers have been received and the client should send the request body (if any). This requires the client to send an Expect: 100-continue header in the request.
If an error code is returned then the client should not send the request body.
If the server is unable to support the Expect header then a 417 will be returned.