public TimestampOffset entry(int n) {
        return maybeLock(lock, () -> {
            if (n >= entries())
                throw new IllegalArgumentException("Attempt to fetch the " + n + "th entry from time index "
                    + file().getAbsolutePath() + " which has size " + entries());
            return parseEntry(mmap(), n);
        });
    }
Get the nth timestamp mapping from the time index
@param n The entry number in the time index
@return The timestamp/offset pair at that entry
storage/src/main/java/org/apache/kafka/storage/internals/log/TimeIndex.java