Today the snmp4j.org web-site has been relaunched and the underlying technology is now responsive HTML5. The content has been streamlined, so you might not find anything from the old page available 2004-2020. If you really miss something, please let me know!
If you - the users of SNMP4J APIs - are still interested in UML diagrams of the major classes like this then I might create a new set of diagrams reflecting the current status/versions of the APIs in the future. Just let me know here in this topic if your are interested.
On the new site you see a preview sample code of the new org.snmp4j.fluent package of SNMP4J 3.5.0 which is available as SNMP4J 3.5.0-SNAPSHOT
This fluent interface facilitates setting up SNMP4J correctly without breaking existing code.
Feedback and suggestions for improvement are welcome! 