public byte[][] getRegionSplitStartKeys(byte[] startKey, byte[] endKey, int numRegions) {
    if (numRegions <= 3) {
      throw new AssertionError();
    }
    byte[][] tmpSplitKeys = Bytes.split(startKey, endKey, numRegions - 3);
    byte[][] result = new byte[tmpSplitKeys.length + 1][];
    System.arraycopy(tmpSplitKeys, 0, result, 1, tmpSplitKeys.length);
    result[0] = HConstants.EMPTY_BYTE_ARRAY;
    return result;
  }
Create region split keys between startkey and endKey
@param numRegions the number of regions to be created. it has to be greater than 3.
@return resulting split keys
hbase-testing-util/src/main/java/org/apache/hadoop/hbase/HBaseTestingUtility.java