From eea02ebf0260f47215a0f767adffb14665893352 Mon Sep 17 00:00:00 2001
From: Sebastian Schmidt <mrschmidt@google.com>
Date: Fri, 20 Apr 2018 14:31:38 +0100
Subject: [PATCH] Allowing non-POJO Firestore classes to be subclassed for
 mocking.

---
 .../com/google/cloud/firestore/CollectionReference.java   | 8 ++++++--
 .../com/google/cloud/firestore/DocumentReference.java     | 6 +++++-
 .../java/com/google/cloud/firestore/DocumentSnapshot.java | 4 ++++
 .../com/google/cloud/firestore/QueryDocumentSnapshot.java | 6 +++++-
 4 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/google-cloud-firestore/src/main/java/com/google/cloud/firestore/CollectionReference.java b/google-cloud-firestore/src/main/java/com/google/cloud/firestore/CollectionReference.java
index cf36d9c51571..fd41c86851c9 100644
--- a/google-cloud-firestore/src/main/java/com/google/cloud/firestore/CollectionReference.java
+++ b/google-cloud-firestore/src/main/java/com/google/cloud/firestore/CollectionReference.java
@@ -26,9 +26,13 @@
 
 /**
  * A CollectionReference can be used for adding documents, getting document references, and querying
- * for documents (using the methods inherited from Query)
+ * for documents (using the methods inherited from Query).
+ *
+ * <p><b>Subclassing Note</b>: Firestore classes are not meant to be subclassed except for use in
+ * test mocks. Subclassing is not supported in production code and new SDK releases may break code
+ * that does so.
  */
-public final class CollectionReference extends Query {
+public class CollectionReference extends Query {
 
   /**
    * Creates a CollectionReference from a complete collection path.
diff --git a/google-cloud-firestore/src/main/java/com/google/cloud/firestore/DocumentReference.java b/google-cloud-firestore/src/main/java/com/google/cloud/firestore/DocumentReference.java
index db57a9a024cb..152cef0e7571 100644
--- a/google-cloud-firestore/src/main/java/com/google/cloud/firestore/DocumentReference.java
+++ b/google-cloud-firestore/src/main/java/com/google/cloud/firestore/DocumentReference.java
@@ -36,8 +36,12 @@
  * write, read, or listen to the location. There may or may not exist a document at the referenced
  * location. A DocumentReference can also be used to create a CollectionReference to a
  * subcollection.
+ *
+ * <p><b>Subclassing Note</b>: Firestore classes are not meant to be subclassed except for use in
+ * test mocks. Subclassing is not supported in production code and new SDK releases may break code
+ * that does so.
  */
-public final class DocumentReference {
+public class DocumentReference {
 
   private final ResourcePath path;
   private final FirestoreImpl firestore;
diff --git a/google-cloud-firestore/src/main/java/com/google/cloud/firestore/DocumentSnapshot.java b/google-cloud-firestore/src/main/java/com/google/cloud/firestore/DocumentSnapshot.java
index a66f4466a0c0..6382464fa65d 100644
--- a/google-cloud-firestore/src/main/java/com/google/cloud/firestore/DocumentSnapshot.java
+++ b/google-cloud-firestore/src/main/java/com/google/cloud/firestore/DocumentSnapshot.java
@@ -41,6 +41,10 @@
  * <p>If the DocumentSnapshot points to a non-existing document, getData() and its corresponding
  * methods will return null. You can always explicitly check for a document's existence by calling
  * {@link #exists()}.
+ *
+ * <p><b>Subclassing Note</b>: Firestore classes are not meant to be subclassed except for use in
+ * test mocks. Subclassing is not supported in production code and new SDK releases may break code
+ * that does so.
  */
 public class DocumentSnapshot {
 
diff --git a/google-cloud-firestore/src/main/java/com/google/cloud/firestore/QueryDocumentSnapshot.java b/google-cloud-firestore/src/main/java/com/google/cloud/firestore/QueryDocumentSnapshot.java
index 2b6955da0db8..3b2809fb275b 100644
--- a/google-cloud-firestore/src/main/java/com/google/cloud/firestore/QueryDocumentSnapshot.java
+++ b/google-cloud-firestore/src/main/java/com/google/cloud/firestore/QueryDocumentSnapshot.java
@@ -32,8 +32,12 @@
  * <p>QueryDocumentSnapshot offers the same API surface as {@link DocumentSnapshot}. Since query
  * results contain only existing documents, the {@link #exists()} method will always return true and
  * {@code getData()} will never be null.
+ *
+ * <p><b>Subclassing Note</b>: Firestore classes are not meant to be subclassed except for use in
+ * test mocks. Subclassing is not supported in production code and new SDK releases may break code
+ * that does so.
  */
-public final class QueryDocumentSnapshot extends DocumentSnapshot {
+public class QueryDocumentSnapshot extends DocumentSnapshot {
   private QueryDocumentSnapshot(
       FirestoreImpl firestore,
       DocumentReference docRef,