public HBaseCluster getHBaseClusterInterface() {
    // implementation note: we should rename this method as #getHBaseCluster(),
    // but this would require refactoring 90+ calls.
    return hbaseCluster;
  }
Returns the HBaseCluster instance.
<p>
Returned object can be any of the subclasses of HBaseCluster, and the tests referring this
should not assume that the cluster is a mini cluster or a distributed one. If the test only
works on a mini cluster, then specific method {@link #getMiniHBaseCluster()} can be used
instead w/o the need to type-cast.
hbase-testing-util/src/main/java/org/apache/hadoop/hbase/HBaseTestingUtility.java