public static Long downsamplerTimestamp(Long millitimestamp,long windowSize){
  return millitimestamp - (millitimestamp % windowSize);
}

public static Long downsamplerTimestamp ( Long millitimestamp , long windowSize ) { return millitimestamp - ( millitimestamp % windowSize ) ; }
creating timestamp for downsampling in order to be consistent with tsdb downsampling func on hour / minute level
