added null handling, fixed bug relating to conversion of non-generic collections

git-svn-id: https://src.springframework.org/svn/spring-framework/trunk@2151 50f2f4bb-b051-0410-bef5-90022cba6387

org.springframework.context/src/main/java/org/springframework/ui/format/support/FormattingConversionServiceAdapter.java

@@ -81,6 +81,9 @@ public class FormattingConversionServiceAdapter extends GenericConversionService
 		}
 
 		public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
+			if (source == null) {
+				return null;
+			}
 			try {
 				return this.formatter.parse((String) source, LocaleContextHolder.getLocale());
 			}