[patch] jsp:getProperty tag prints "null" to page when object is null.

[Ben Souther <bp...@adelphia.net>]

In version 4x and earlier, a jsp:getProperty tag will print a zero length 
string to the page if the bean's property value is null.

In version 5x it prints the string "null".

I don't know if this is a bug or an intentional change but I know it will 
cause headaches for developers moving existing apps to version 5.

The attached patch applies to 
org.apache.jasper.runtime.JspRuntimeLibrary.java  

Thank you,
Ben Souther