Lambda not received "client-context"

I read this:https://docs.aws.amazon.com/lambda/latest/dg/python-context-object.html.
I think code is can receive "conext.client_context.custom" children. by this invoke.

aws lambda invoke --function-name "targetlambda" --invocation-type RequestResponse --client-context "eyJjb3VzdG9tIjp7ImZpenoiOiJidXp6In19" "output"

but.can't received this.
I try changing Runtime for Lambda to "Node.js 10.x". Result is success.Node.js Lambda can received.

client-context generated by javascript oneliner.

window.btoa(JSON.stringify({"coustom":{"fizz":"buzz"}}))