Use Open Cloud via HttpService Without Proxies

[Dhammapada]

Calling to accept/decline returns that the json format is not valid, despite following the documentation:

Below is example code where I placed my own userId, but using users that are pending to join the group has the same response.

From within a server script in Studio:

local function handleGroupRequest(player: Player, shouldAccept: boolean)
	if shouldAccept == nil then
		warn(string.format("shouldAccept is nil for player %s", player))
		return
	end

	local joinRequestId = player.UserId
	local groupId = 6483054
	local state = shouldAccept and "accept" or "decline"

	local url = string.format(
		"https://apis.roblox.com/cloud/v2/groups/%d/join-requests/%d:%s",
		groupId,
		joinRequestId,
		state
	)
	print("Request URL:", url)

	local success, response = pcall(HttpService.RequestAsync, HttpService, {
		Url = url,
		Method = "POST",
		Headers = {
			["Content-Type"] = "application/json",
			["x-api-key"] = HttpService:GetSecret("TEST_KEY"),
		},
		Body = HttpService:JSONEncode({})
	})

	if success and response.Success then
		print("The response was successful:", response.StatusCode)
	else
		warn("The response returned an error:", response)
	end

	if success and response.Body then
		local decoded = HttpService:JSONDecode(response.Body)
		print("Response body:\n", printTable(decoded))
	end
end