preconditionRequired constant
int
const preconditionRequired
preconditionRequired = 428.
The origin server requires the request to be conditional.
Intended to prevent the 'lost update' problem, where a client GETs a resource's state, modifies it, and PUTs it back to the server, when meanwhile a third party has modified the state on the server, leading to a conflict.
Implementation
static const int preconditionRequired = 428;