{
  "grant_type": "refresh_token",
  "client_id": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
  "client_secret": "12345678-abcd-efgh-ijkl-9876543210ab",
  "redirect_uri": "https://myapp.example.com/oauth/callback",
  "code": "abc123def456",
  "refresh_token": "6f18f26a-3e95-4d95-a6e5-3d5c6e5c9e5a"
}