New EmptyFileException, and fix serial warning

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1677561 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/EmptyFileException.java

@@ -0,0 +1,28 @@
+/* ====================================================================
+   Licensed to the Apache Software Foundation (ASF) under one or more
+   contributor license agreements.  See the NOTICE file distributed with
+   this work for additional information regarding copyright ownership.
+   The ASF licenses this file to You under the Apache License, Version 2.0
+   (the "License"); you may not use this file except in compliance with
+   the License.  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+==================================================================== */
+package org.apache.poi;
+
+/**
+ * Exception thrown if an Empty (zero byte) file is supplied
+ */
+public class EmptyFileException extends IllegalArgumentException {
+    private static final long serialVersionUID = 1536449292174360166L;
+
+    public EmptyFileException() {
+		super("The supplied file was empty (zero bytes long)");
+	}
+}

src/java/org/apache/poi/EncryptedDocumentException.java

@@ -16,9 +16,10 @@
 ==================================================================== */
 package org.apache.poi;
 
-@SuppressWarnings("serial")
 public class EncryptedDocumentException extends IllegalStateException
 {
+    private static final long serialVersionUID = 7276950444540469193L;
+    
 	public EncryptedDocumentException(String s) {
 		super(s);
 	}