private void warmUpConnectionCache(Connection connection, TableName tn) throws IOException {
    try (RegionLocator locator = connection.getRegionLocator(tn)) {
      LOG.info("Warmed up region location cache for " + tn + " got "
        + locator.getAllRegionLocations().size());
    }
  }
For the example we're just using one qualifier.
hbase-examples/src/main/java/org/apache/hadoop/hbase/client/example/MultiThreadedClientExample.java