fix bug: encode batch in header

[yichenluan]

What is the purpose of the change

Fix a bug:
take out comment on encode batch to header

Brief changelog

fix bug: encode batch in header

Verifying this change

build and test

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[yichenluan]

This is a serious bug, please merge it ASAP.

@ShannonDing @ifplusor

[jonnxu]

modify not correct, reference to #152

[yichenluan]

In practice, "batch" in requestMap is unnecessary

[ShannonDing]

close it due to duplicate.