code: public static boolean hasAmazonClasses() {
          boolean result;
          synchronized (AmazonAppstore.class) {
              try {
                  ClassLoader localClassLoader = AmazonAppstore.class.getClassLoader();
                  localClassLoader.loadClass("com.amazon.android.Kiwi");
                  result = true;
              } catch (Throwable localThrowable) {
                  Logger.d("hasAmazonClasses() cannot load class com.amazon.android.Kiwi");
                  result = false;
              }
          }
          return result;
      }
docs: Tries to load Amazon <code>com.amazon.android.Kiwi</code> class.
  <p/>
  Submitted .apk is not published to Amazon as is. It is re-packed with several Amazon-specific
  classes. We examine such classes to understand whether app is delivered by Amazon