curl -vsH "Content-Type: application/json" \
  -X GET 'https://firestore.googleapis.com/v1beta1/projects/projectIDhere/databases/(default)/documents/collectionName'


{
  "documents": [
    {
      "name": "projects/projectIDhere/databases/(default)/documents/collectionName/documentID01",
      "fields": {
        "name": {
          "stringValue": "test1"
        },
        "name2": {
          "stringValue": "test2"
        }
      },
      "createTime": "2018-01-16T05:50:16.345709Z",
      "updateTime": "2018-01-16T05:50:16.345709Z"
    },
    {
      "name": "projects/projectIDhere/databases/(default)/documents/collectionName/documentID02",
      "fields": {
        "name": {
          "stringValue": "test3"
        }
      },
      "createTime": "2018-01-16T05:59:36.023982Z",
      "updateTime": "2018-01-16T05:59:36.023982Z"
    }
  ]
}