check
Checks if the given element passes the idempotency test. Returns true if the element is considered unique (not a duplicate), false if it's a duplicate. The check is performed asynchronously and returns a Mono for reactive programming compatibility.
Return
a Mono emitting true if the element passes the idempotency check (is unique), false if it's a duplicate
Parameters
element
the element to check for idempotency (typically a command or request identifier)