public boolean isEmpty() {
    return this.holes.isEmpty() && this.overlaps.isEmpty() && this.unknownServers.isEmpty()
      && this.emptyRegionInfo.isEmpty();
  }
Returns True if an 'empty' lastReport -- no problems found.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/janitor/CatalogJanitorReport.java