This remove a breaking change introduced with commit #e7a8e2757b06d572f614f53b648d2fd75df370d2 where json objects passed to requests were not converted into string.
BREAKING CHANGE:
The behavior in this commit is the same as before PR 7260 : the objects sent with the request are converted to a string, therefore there is no need for the user to take care of the serialization.
Fixes#10073