@Override
      public boolean evaluate() {
        return generatedRegions.stream()
          .mapToDouble(val -> getRegionSizeMB(master, val.getRegionInfo())).allMatch(val -> val > 0)
          && getRegionSizeMB(master, generatedRegions.get(4).getRegionInfo()) >= 4.0;
      }
create a table with 5 regions, having region sizes so as to provoke a split of the largest
region.
<ul>
<li>total table size: 12</li>
<li>average region size: 2.4</li>
<li>split threshold: 2.4 * 2 = 4.8</li>
</ul>
hbase-server/src/test/java/org/apache/hadoop/hbase/master/normalizer/TestSimpleRegionNormalizerOnCluster.java