added a slightly better reason for why this class is of importance

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/io/trunk@140412 13f79535-47bb-0310-9956-ffa450edef68

Author: hen

src/java/org/apache/commons/io/input/ProxyInputStream.java

@@ -61,7 +61,8 @@
  * A Proxy stream which acts as expected, that is it passes the method 
  * calls on to the proxied stream and doesn't change which methods are 
  * being called. It is an alternative base class to FilterInputStream
- * to increase reusability.
+ * to increase reusability, because FilterInputStream changes the 
+ * methods being called, such as read(byte[]) to read(byte[], int, int).
  */
 public abstract class ProxyInputStream extends FilterInputStream {