Add android channel id support (#224)

* Add android channel id support

* Add android channel id support

CHANGELOG.md

@@ -13,6 +13,9 @@
   that are helpful when debugging problems.
 - [changed] Migrated the `FirebaseAuth` user management API to the
   new Identity Toolkit endpoint.
+- [added] Added new `setChannelId()` to the 
+  AndroidNotification.Builder API for setting the Android 
+  notification channel ID (new in Android O).
 
 # v6.5.0
 

src/main/java/com/google/firebase/messaging/AndroidNotification.java

@@ -63,6 +63,9 @@ public class AndroidNotification {
 
   @Key("title_loc_args")
   private final List<String> titleLocArgs;
+
+  @Key("channel_id")
+  private final String channelId;
 
   private AndroidNotification(Builder builder) {
     this.title = builder.title;
@@ -93,6 +96,7 @@ private AndroidNotification(Builder builder) {
     } else {
       this.titleLocArgs = null;
     }
+    this.channelId = builder.channelId;
   }
 
   /**
@@ -117,6 +121,7 @@ public static class Builder {
     private List<String> bodyLocArgs = new ArrayList<>();
     private String titleLocKey;
     private List<String> titleLocArgs = new ArrayList<>();
+    private String channelId;
 
     private Builder() {}
 
@@ -273,6 +278,20 @@ public Builder addAllTitleLocalizationArgs(@NonNull List<String> args) {
       return this;
     }
 
+    /**
+     * Sets the Android notification channel ID (new in Android O). The app must create a channel
+     * with this channel ID before any notification with this channel ID is received. If you 
+     * don't send this channel ID in the request, or if the channel ID provided has not yet been
+     * created by the app, FCM uses the channel ID specified in the app manifest.
+     *
+     * @param channelId The notification's channel ID.
+     * @return This builder.
+     */
+    public Builder setChannelId(String channelId) {
+      this.channelId = channelId;
+      return this;
+    }
+
     /**
      * Creates a new {@link AndroidNotification} instance from the parameters set on this builder.
      *

src/test/java/com/google/firebase/messaging/FirebaseMessagingTest.java

@@ -606,6 +606,7 @@ private static Map<Message, Map<String, Object>> buildTestMessages() {
                     .addAllTitleLocalizationArgs(ImmutableList.of("t-arg2", "t-arg3"))
                     .addBodyLocalizationArg("b-arg1")
                     .addAllBodyLocalizationArgs(ImmutableList.of("b-arg2", "b-arg3"))
+                    .setChannelId("channel-id")
                     .build())
                 .build())
             .setTopic("test-topic")
@@ -629,6 +630,7 @@ private static Map<Message, Map<String, Object>> buildTestMessages() {
                     .put("title_loc_args", ImmutableList.of("t-arg1", "t-arg2", "t-arg3"))
                     .put("body_loc_key", "test-body-key")
                     .put("body_loc_args", ImmutableList.of("b-arg1", "b-arg2", "b-arg3"))
+                    .put("channel_id", "channel-id")
                     .build()
             )
         ));

src/test/java/com/google/firebase/messaging/MessageTest.java

@@ -147,6 +147,7 @@ public void testAndroidMessageWithNotification() throws IOException {
                 .setBodyLocalizationKey("body-loc")
                 .addBodyLocalizationArg("body-arg1")
                 .addAllBodyLocalizationArgs(ImmutableList.of("body-arg2", "body-arg3"))
+                .setChannelId("channel-id")
                 .build())
             .build())
         .setTopic("test-topic")
@@ -163,6 +164,7 @@ public void testAndroidMessageWithNotification() throws IOException {
         .put("title_loc_args", ImmutableList.of("title-arg1", "title-arg2", "title-arg3"))
         .put("body_loc_key", "body-loc")
         .put("body_loc_args", ImmutableList.of("body-arg1", "body-arg2", "body-arg3"))
+        .put("channel_id", "channel-id")
         .build();
     Map<String, Object> data = ImmutableMap.of(
         "collapse_key", "test-key",