in src/main/java/org/apache/cassandra/distributed/shared/MessageFilters.java [119:125]
public boolean matches(int from, int to, IMessage msg)
{
return (this.from == null || Arrays.binarySearch(this.from, from) >= 0)
&& (this.to == null || Arrays.binarySearch(this.to, to) >= 0)
&& (this.verbs == null || Arrays.binarySearch(this.verbs, msg.verb()) >= 0)
&& (this.matcher == null || this.matcher.matches(from, to, msg));
}