Test extents having a different type of the same field.
the field 'price' is of type double in Article and String in BookArticle
author: Jakob Braeuchi version: $Id: FieldTypeTest.java,v 1.1.2.2 2005/12/21 22:31:23 tomdz Exp $
Inner Class :public static class AbstractArticle
Inner Class :public static class Article extends AbstractArticle
Inner Class :public static class BookArticle extends AbstractArticle
Inner Class :public static class DoubleToStringConversion implements FieldConversion