curl --request POST \
--url https://api-staging.respondent.io/v1/messaging/conversations/{conversationUid}/participants \
--header 'Content-Type: application/json' \
--header 'x-api-key: <x-api-key>' \
--header 'x-api-secret: <x-api-secret>' \
--data '{
"participantUserId": "<string>"
}'