why use nested interfaces ?
I was reading Apache Cassandra's code base when I came across nested interfaces, now I know what an interface is but I did not understand why would you and when would you use a nested interface ?
public interface Memtable extends Comparable<Memtable>, UnfilteredSource, CellSourceIdentifier
{
public static final long NO_MIN_TIMESTAMP = -1;
interface Factory
{
/**
* Create a memtable.
...