android: make onExternalAPIEvent protected

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

      * @param data - The details of the event associated with/specific to the
      * specified {@code name}.
      */
-    public abstract void onExternalAPIEvent(String name, ReadableMap data);
+    protected abstract void onExternalAPIEvent(String name, ReadableMap data);
 
     protected void onExternalAPIEvent(
             Map<String, Method> listenerMethods,

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

      * by/associated with the specified {@code name}.
      */
     @Override
-    public void onExternalAPIEvent(String name, ReadableMap data) {
+    protected void onExternalAPIEvent(String name, ReadableMap data) {
         // XXX The JitsiMeetView property URL was introduced in order to address
         // an exception in the Picture-in-Picture functionality which arose
         // because of delays related to bridging between JavaScript and Java. To

android/sdk/src/main/java/org/jitsi/meet/sdk/incoming_call/IncomingCallView.java

      * by/associated with the specified {@code name}.
      */
     @Override
-    public void onExternalAPIEvent(String name, ReadableMap data) {
+    protected void onExternalAPIEvent(String name, ReadableMap data) {
         onExternalAPIEvent(LISTENER_METHODS, name, data);
     }