Use Timestamp in Date fields (firebase#79)

Author: samtstern

firestore/app/src/main/java/com/google/example/firestore/DocSnippets.java

@@ -10,6 +10,7 @@
 import com.google.android.gms.tasks.OnSuccessListener;
 import com.google.android.gms.tasks.Task;
 import com.google.android.gms.tasks.Tasks;
+import com.google.firebase.Timestamp;
 import com.google.firebase.firestore.CollectionReference;
 import com.google.firebase.firestore.DocumentChange;
 import com.google.firebase.firestore.DocumentChange.Type;
@@ -349,7 +350,7 @@ public void dataTypes() {
         docData.put("stringExample", "Hello world!");
         docData.put("booleanExample", true);
         docData.put("numberExample", 3.14159265);
-        docData.put("dateExample", new Date());
+        docData.put("dateExample", new Timestamp(new Date()));
         docData.put("listExample", Arrays.asList(1, 2, 3));
         docData.put("nullExample", null);
 

firestore/app/src/main/java/com/google/example/firestore/kotlin/DocSnippets.kt

@@ -6,6 +6,7 @@ import android.support.annotation.WorkerThread
 import android.util.Log
 import com.google.android.gms.tasks.Task
 import com.google.android.gms.tasks.Tasks
+import com.google.firebase.Timestamp
 import com.google.firebase.firestore.CollectionReference
 import com.google.firebase.firestore.DocumentChange
 import com.google.firebase.firestore.DocumentSnapshot
@@ -256,7 +257,7 @@ abstract class DocSnippets(val db: FirebaseFirestore) {
         docData["stringExample"] = "Hello world!"
         docData["booleanExample"] = true
         docData["numberExample"] = 3.14159265
-        docData["dateExample"] = Date()
+        docData["dateExample"] = Timestamp(Date())
         docData["listExample"] = arrayListOf(1, 2, 3)
         docData["nullExample"] = null