[RN] Add JitsiMeetViewAbstractListener to Android SDK

android/README.md

 Called before a conference is left.
 
 The `data` HashMap contains a "url" key with the conference URL.
+
+### JitsiMeetViewAbstractListener
+
+Utility (abstract) class with stub methods for the `JitsiMeetView.Listener`
+interface. Applications can innherit from this class instead of implementing
+the interface in order to avoid adding stubs for methods they don't care about.
+

android/sdk/src/main/java/org/jitsi/meet/sdk/JitsiMeetViewAbstractListener.java

+/*
+ * Copyright @ 2017-present Atlassian Pty Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jitsi.meet.sdk;
+
+import java.util.HashMap;
+
+/**
+ * This class provides a reference implementation for {@JitsiMeetView.Listener} so applications
+ * don't need to add stubs for all methods in the interface if they are only interested in some.
+ */
+public abstract class JitsiMeetViewAbstractListener implements JitsiMeetView.Listener {
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void onConferenceFailed(HashMap<String, Object> data) {
+
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void onConferenceJoined(HashMap<String, Object> data) {
+
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void onConferenceLeft(HashMap<String, Object> data) {
+
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void onConferenceWillJoin(HashMap<String, Object> data) {
+
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void onConferenceWillLeave(HashMap<String, Object> data) {
+
+    }
+}

android/sdk/src/main/java/org/jitsi/meet/sdk/externalapi/ExternalAPIModule.java

         // until React Native 0.46.
         final HashMap<String, Object> dataMap = new HashMap<>();
 
-        try {
-            switch (name) {
-            case "CONFERENCE_FAILED":
-                dataMap.put("error", data.getString("error"));
-                dataMap.put("url", data.getString("url"));
-                listener.onConferenceFailed(dataMap);
-                break;
-            case "CONFERENCE_JOINED":
-                dataMap.put("url", data.getString("url"));
-                listener.onConferenceJoined(dataMap);
-                break;
-            case "CONFERENCE_LEFT":
-                dataMap.put("url", data.getString("url"));
-                listener.onConferenceLeft(dataMap);
-                break;
-            case "CONFERENCE_WILL_JOIN":
-                dataMap.put("url", data.getString("url"));
-                listener.onConferenceWillJoin(dataMap);
-                break;
-            case "CONFERENCE_WILL_LEAVE":
-                dataMap.put("url", data.getString("url"));
-                listener.onConferenceWillLeave(dataMap);
-                break;
-            }
-        } catch (UnsupportedOperationException e) {
-            // Allow partial interface implementations.
+        switch (name) {
+        case "CONFERENCE_FAILED":
+            dataMap.put("error", data.getString("error"));
+            dataMap.put("url", data.getString("url"));
+            listener.onConferenceFailed(dataMap);
+            break;
+        case "CONFERENCE_JOINED":
+            dataMap.put("url", data.getString("url"));
+            listener.onConferenceJoined(dataMap);
+            break;
+        case "CONFERENCE_LEFT":
+            dataMap.put("url", data.getString("url"));
+            listener.onConferenceLeft(dataMap);
+            break;
+        case "CONFERENCE_WILL_JOIN":
+            dataMap.put("url", data.getString("url"));
+            listener.onConferenceWillJoin(dataMap);
+            break;
+        case "CONFERENCE_WILL_LEAVE":
+            dataMap.put("url", data.getString("url"));
+            listener.onConferenceWillLeave(dataMap);
+            break;
         }
     }
 }