@Override
    public String toString() {
        return "FlushStatusCheckpoint{" + "segFilename='" + fileName + '\'' + ", flushPosition=" + flushPosition
               + ", lastLogIndex=" + lastLogIndex + '}';
    }
flushPosition (8 bytes) + lastLogIndex (8 bytes) + path(4 bytes len + string bytes)
jraft-extension/java-log-storage-impl/src/main/java/com/alipay/sofa/jraft/storage/file/assit/FlushStatusCheckpoint.java