Triggered when a user joins a workspace

{
  "version": "0.0.1",
  "type": "workspace.user_joined",
  "triggered_at": "<string>",
  "user": {
    "profile_id": "<string>",
    "created_at": "<string>",
    "preferred_name": "<string>",
    "preferred_image_original": "<string>",
    "preferred_image_1024": "<string>",
    "preferred_image_512": "<string>",
    "preferred_image_192": "<string>",
    "preferred_image_72": "<string>",
    "preferred_image_48": "<string>",
    "preferred_image_32": "<string>",
    "preferred_image_24": "<string>",
    "first_name": "<string>",
    "last_name": "<string>",
    "email": "<string>",
    "slack_user_id": "<string>",
    "slack_is_admin": true,
    "slack_is_bot": true,
    "slack_first_name": "<string>",
    "slack_last_name": "<string>",
    "slack_image_72": "<string>",
    "slack_image_original": "<string>",
    "profile_fields": {}
  }
}