Proof using.
unfold getNextIndex.
intros.
repeat find_rewrite.
auto.
Qed.

Lemma replicaMessage_ext :
forall st st' h h',
nextIndex st' = nextIndex st ->
log st' = log st ->
currentTerm st' = currentTerm st ->
commitIndex st' = commitIndex st ->
replicaMessage st' h h' = replicaMessage st h h'.