The Java Samples document in the information center is linked to the java samples source. The PluginEx.Java section of this source is not up to date. For current information on Extending the Control Center, see the Java Samples README file, the PluginEx.java file and 9.2, Example for Extending Control Center.
On Windows platforms, the README and PluginEx.java files can be found in x:\sqllib\samples\java where x is the drive on which DB2 is installed.
On UNIX, the README and PluginEx.java files can be found in /u/db2inst1/sqllib/samples/java where /u/db2inst1 represents the directory in which DB2 is installed.