apollo-common/src/main/java/com/ctrip/framework/apollo/common/utils/UniqueKeyGenerator.java/UniqueKeyGenerator/toByteArray
class UniqueKeyGenerator:  protected static byte[] toByteArray(int keyHashCode, int machineIdentifier, int counter) {
    byte[] bytes = new byte[8];
    bytes[0] = ByteUtil.int1(keyHashCode);
    bytes[1] = ByteUtil.int0(keyHashCode);
    bytes[2] = ByteUtil.int2(machineIdentifier);
    bytes[3] = ByteUtil.int1(machineIdentifier);
    bytes[4] = ByteUtil.int0(machineIdentifier);
    bytes[5] = ByteUtil.int2(counter);
    bytes[6] = ByteUtil.int1(counter);
    bytes[7] = ByteUtil.int0(counter);
    return bytes;
  }