+ /**
+ * Exception that signals the addition of a field with an empty name.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+ public static class EmptyFieldName extends IllegalArgumentException { }
+
+ /**
+ * Exception that signals the addition of a field that already exists.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+ public static class DuplicateField extends IllegalArgumentException { }
+