Minor change to fix WW-5072 (single file upload failure):

- Add action-local method to get upload file size.
- Change file upload validation to use new method.

apps/showcase/src/main/java/org/apache/struts2/showcase/fileupload/FileUploadAction.java

@@ -84,4 +84,12 @@ public class FileUploadAction extends ActionSupport {
 	public void setCaption(String caption) {
 		this.caption = caption;
 	}
+
+        public long getUploadSize() {
+            if (upload != null) {
+                return upload.length();
+            } else {
+                return 0;
+            }
+        }
 }

apps/showcase/src/main/resources/org/apache/struts2/showcase/fileupload/FileUploadAction-validation.xml

@@ -26,7 +26,7 @@
 <validators>
 	<field name="upload">
 		<field-validator type="fieldexpression">
-			<param name="expression"><![CDATA[upload.length() > 0]]></param>
+			<param name="expression"><![CDATA[getUploadSize() > 0]]></param>
 			<message>File cannot be empty</message>
 		</field-validator>
 	</field>