Add a user to a Group via Yammer REST API

addusertoyammergroup.json

Method - POST
URI - https://www.yammer.com/api/v1/group_memberships.json
Headers - 
{
  "Authorization": "Bearer @{variables('YammerAccessToken')}",
  "content-type": "application/json; charset=utf-8"
}
Body - 
{
  "user_id": "@{variables('User_id')}",
  "group_id": "@{variables('YammerDestinationGroup')}",
  "email": "@{variables('Email')}"
}