@Override
  public boolean hasNext() {
    if (current.hasNext()) return true;
    this.index++;
    if (this.index >= this.bcs.length) return false;
    this.current = this.bcs[this.index].iterator();
    return hasNext();
  }
Iterator over an array of BlockCache CachedBlocks.
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/BlockCachesIterator.java