code: public static byte[][] getSplitKeys(Pair<byte[][],byte[][]> regionStartsEnds) {
          byte[][] starts = regionStartsEnds.getFirst();
          
          List<byte[]> splitKeys = new ArrayList<byte[]>();
          for(int i=1; i<starts.length; i++) {
              splitKeys.add(starts[i]);
          }
          return splitKeys.toArray(new byte[][] {});
      }
docs: Get the non-null non-null non-zero-length row keys that divide the regions