default CompletableFuture<List<byte[]>> getStartKeys() {
    return getStartEndKeys().thenApply(
      startEndKeys -> startEndKeys.stream().map(Pair::getFirst).collect(Collectors.toList()));
  }
Gets the starting row key for every region in the currently open table.
<p>
This is mainly useful for the MapReduce integration.
@return Array of region starting row keys
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncTableRegionLocator.java