rotateNonce method
Makes a new nonce; the current one becomes the previous one, an older one is stale.
Implementation
void rotateNonce() {
_previous = _current;
_current = 'nonce-${++_nonces}';
}Makes a new nonce; the current one becomes the previous one, an older one is stale.
void rotateNonce() {
_previous = _current;
_current = 'nonce-${++_nonces}';
}