Add serialization version ID

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@1077922 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/src/main/java/org/apache/commons/lang3/builder/ToStringStyle.java b/src/main/java/org/apache/commons/lang3/builder/ToStringStyle.java
index 6df1e6d..3f1dee1 100644
--- a/src/main/java/org/apache/commons/lang3/builder/ToStringStyle.java
+++ b/src/main/java/org/apache/commons/lang3/builder/ToStringStyle.java
@@ -70,6 +70,11 @@
 public abstract class ToStringStyle implements Serializable {
 
     /**
+     * Serialization version ID.
+     */
+    private static final long serialVersionUID = -2587890625525655916L;
+
+    /**
      * The default toString style. Using the Using the <code>Person</code>
      * example from {@link ToStringBuilder}, the output would look like this:
      *