I think it should look something like:
files { gsc { contents: """{"type": "service_account", "project_id": "ai-platform", "private_key_id": "9999", "private_key": "-----BEGIN PRIVATE KEY-----==\n-----END PRIVATE KEY-----\n", "client_email": "a@ai.iam.gserviceaccount.com", "client_id": "111", "auth_uri": " ", "token_uri": " ", "auth_provider_x509_cert_url": " ", "client_x509_cert_url": " "}""" path: "~/gs.cred" } }