code: public Cursor<SingleValue> readSingleValue(Filter filter, DateTime timestamp) {
      return readSingleValue(filter, timestamp, DateTimeZone.getDefault(), Direction.EXACT);
    }
docs: Returns a cursor of single value for a set of series
  <p>The returned values (datapoints) can be null if there are no
  datapoints in the series or in the specified direction. The
  system default timezone is used. The direction is set to EXACT.
  
  @param filter The filter of series to read from
  @param timestamp The timestamp to read a value at
  @return A cursor over the values at the specified timestamp
  
  @see Cursor
  @see SingleValue
  @since 1.1.0