如何向datax传递空参数？

json配置文件片段如下:"reader": {
"name": "mysqlreader",
"parameter": {
"splitPk": "$splitPk",
"column": ["perio_id","release_cycle","issue_scope","total_articles","circulation","avg_article_down"],
datax文档里说：如果splitPk不填写，包括不提供splitPk或者splitPk值为空，DataX视作使用单通道同步该表数据。
如果我想传空参数，提交命令应该怎么写呢？我现在写成 -p "-DsplitPk=“、-p "-DsplitPk=''"都是不对的。

Review the DataX documentation for mysqlreader's splitPk option and command-line parameter handling, using the shown JSON and both -p forms as examples. Done means documenting the supported syntax for an omitted or empty splitPk value and making the single-channel behavior unambiguous.

Written by the indexing model from the issue text.