- Added Resource#toRepresentation(Object, MediaType) convenience method.
      - Added ConverterService#toRepresentation(Object, MediaType) convenience method.
      - Added ConverterService#toRepresentation(Object, Variant) convenience method.
      - Added static Resource#toInteger, toFloat, toByte, toLong, toDouble, toBoolean
        methods accepting 'null' string values to facilitate the processing of path
        variables and query parameters.