-keep class com.android.vending.billing.**

-assumenosideeffects class org.solovyev.android.checkout.Billing {
    public static void debug(...);
    public static void warning(...);
    public static void error(...);
}

-assumenosideeffects class org.solovyev.android.checkout.Check {
    static *;
}

-keepclassmembers enum * {
    public static **[] values();
    public static ** valueOf(java.lang.String);
}