boolean maybeAcquireFetchLock() {
        return fetchLock.compareAndSet(false, true);
    }
Prior to fetching records from the leader, the fetch lock is acquired to ensure that the same
share partition does not enter a fetch queue while another one is being fetched within the queue.
The fetch lock is released once the records are fetched from the leader.

@return A boolean which indicates whether the fetch lock is acquired.
core/src/main/java/kafka/server/share/SharePartition.java