RxJava NoSuchFieldException: producerIndex error when using proguard in Android Studio

There is an error of RxJava when generating signed apk using proguard in Android Studio.
The solution in my case is this link. Add the following at the proguard rules.

-keepclassmembers class rx.internal.util.unsafe.*ArrayQueue*Field* {
    long producerIndex;
    long consumerIndex;
}
-keepclassmembers class rx.internal.util.unsafe.BaseLinkedQueueProducerNodeRef {
    long producerNode;
    long consumerNode;
}