added comment
diff --git a/android-project/src/org/libsdl/app/SDLActivity.java b/android-project/src/org/libsdl/app/SDLActivity.java
index 25cb789..28d461c 100644
--- a/android-project/src/org/libsdl/app/SDLActivity.java
+++ b/android-project/src/org/libsdl/app/SDLActivity.java
@@ -514,6 +514,8 @@
             Integer patchVersion = Integer.parseInt(nativeGetHint("SDL_ANDROID_APK_EXPANSION_PATCH_FILE_VERSION"));
 
             try {
+                // To avoid direct dependency on Google APK extension library that is
+                // not a part of Android SDK we access it using reflection
                 expansionFile = Class.forName("com.android.vending.expansion.zipfile.APKExpansionSupport")
                     .getMethod("getAPKExpansionZipFile", Context.class, int.class, int.class)
                     .invoke(null, this, mainVersion, patchVersion);