in services/image-analysis/java/src/main/java/services/EventService.java [31:40]
public ApiFuture<WriteResult> storeImage(String fileName, List<String> labels, String mainColor) {
DocumentReference doc = firestore.collection("pictures").document(fileName);
Map<String, Object> data = new HashMap<>();
data.put("labels", labels);
data.put("color", mainColor);
data.put("created", new Date());
return doc.set(data, SetOptions.merge());
}