code: public Envelope convert(String inputString)
              throws TypeConversionException {
          double[] coordinates = getCoordinates(inputString);
          return createEnvelope(coordinates);
      }
docs: Converts the given string into an Envelope.
  <br>
  The inputstring is simply a list of 4 doubles seperated by a , The first two numbers are the first
  corner of the envelope, the two last make up the second corner. If there are more than 4 numbers present,
  all numbers are ignored except for the first 4. If there are less than 4 or if the string contains other
  data except for the expected numberlist, a typeconversionexception is thrown.     *
  
  @param inputString The inputstring
  @return An envelope that consists of the given coordinates.
  @throws TypeConversionException If the string is invalid and can not be converted into an object of T.
  @see TypeConverter#convert(String)