Exemplo de evento de retorno de chamada do Dropbox Sign

{
 "event": {
 "event_type": "signature_request_sent",
 "event_time": "1525470811",
 "event_hash": "e3f253402d44dcc16e5ecc5972e87c4ec32c0bb4027a130a5b700b7851ab74d1",
 "event_metadata": {
 "related_signature_id": null,
 "reported_for_account_id": "615266b89aeda4e8cd2f2a5d401dbc76f4fa",
 "reported_for_app_id": "ff3366f5236b94b4ded1aeecfc2"
 }
 },
 "account_guid": "615266b89aeda4e8cd2f2a5d401dbc76f4fa",
 "client_id": "ff3366f5236b94b4ded1aeecfc2",
 "signature_request": {
 "signature_request_id": "21bb8f947df4ad622c103f662543b230b713d",
 "test_mode": false,
 "title": "Título da solicitação de assinatura",
 "original_title": "Título original da solicitação de assinatura",
 "subject": null,
 "message": "Por favor, assine este documento.",
    "metadata": {},
 "attachments": [
 {
 "id": "59c7ad1be6af226637c3d4dbfe4a801ff630e",
 "signer": 1,
 "name": "Licença",
 "instructions": "Adicione sua licença",
 "required": true,
 "uploaded_at": null
 }
 ],
 "is_complete": false,
 "is_declined": false,
 "has_error": false,
 "custom_fields": [],
 "response_data": [],
 "signing_url": null,
 "signing_redirect_url": null,
 "final_copy_uri": "/v3/signature_request/final_copy/21bb8f947df4ad622c103f662543b230b713d",
 "files_url": "https://api.hellosign.com/v3/signature_request/files/21bb8f947df4ad622c103f662543b230b713d",
    "details_url": "https://app.hellosign.com/home/manage?guid=21bb8f947df4ad622c103f662543b230b713d", 
 "requester_email_address": "teste@exemplo.com",
    "signatures": [
 {
 "signature_id": "e53ed08286e83e421f061912a0cb1",
 "has_pin": false,
 "signer_email_address": "signatario@exemplo.com",
 "signer_name": "Primeiro signatário",
 "order": null,
 "status_code": "awaiting_signature",
 "signed_at": null,
 "last_viewed_at": null,
 "last_reminded_at": null,
 "error": null
 }
 ],
 "cc_email_addresses": []
 }
}