code: public static long getTimestampFromRollupQualifier(final byte[] qualifier, 
                    final long base_time, 
                    final RollupInterval interval,
                    final int offset) {
      return (base_time * 1000) + 
              getOffsetFromRollupQualifier(qualifier, offset, interval);
    }
docs: Returns the absolute timestamp of a data point qualifier in milliseconds
  @param qualifier The qualifier to parse
  @param base_time The base time, in seconds, from the row key
  @param interval The RollupInterval object with data about the interval
  @param offset An offset within the byte array
  @return The absolute timestamp in milliseconds