public static boolean isProxyClass(Class<?> c) {
    // TODO: use a marker interface instead?
    try {
      c.getDeclaredField(FIELD_NAME_HANDLER);
      return true;
    } catch (NoSuchFieldException e) {
      return false;
    }
  }
Returns true if {@code c} is a proxy class created by this builder.
android/android_framework/dex-maker/src/main/java/com/android/dx/stock/ProxyBuilder.java