code: public static BigDecimal toBigDecimal(long universalTime, int timeScale)
      {
          TimeScaleData data     = getTimeScaleData(timeScale);
          BigDecimal universal   = new BigDecimal(universalTime);
          BigDecimal units       = new BigDecimal(data.units);
          BigDecimal epochOffset = new BigDecimal(data.epochOffset);
          
          return universal.divide(units, BigDecimal.ROUND_HALF_UP).subtract(epochOffset);
      }
docs: Convert a datetime from the universal time scale to a <code>BigDecimal</code> in the given time scale.
  
  @param universalTime The datetime in the universal time scale
  @param timeScale The time scale to convert to
  
  @return The datetime converted to the given time scale