public static File offsetIndexFile(File dir, long offset) {
        return offsetIndexFile(dir, offset, "");
    }
Construct an index file name in the given dir using the given base offset.

@param dir    The directory in which the log will reside
@param offset The base offset of the log file
storage/src/main/java/org/apache/kafka/storage/internals/log/LogFileUtils.java