How many bytes is taken by the payload header. Header is defined here as protocol definition +
length. Most common value here is four bytes, so we keep that as default. Effectively, this is
how much of the message you "don't" want to read from the message's total length with readAll.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025年10月30日 UTC."],[],[]]