@Override
    public String toString() {
        return "op=" + op + ", k=" + key + (value == null ? "" : ", v=" + value) + ", timestamp=" + timestamp;
    }
@author Robert HG (254963746@qq.com) on 12/13/15.
lts-core/src/main/java/com/github/ltsopensource/kv/txlog/StoreTxLogEntry.java