public void setFlushPosition(final long flushPosition) {
        this.flushPosition = flushPosition;
    }
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