There is a collection of resources available at https://toolbox.opennms.eu/ that may come in handy. This site will have links to OpenNMS resources as well as some tools for troubleshooting.
Note: The use of paste tools is not recommended here as code/log samples should be embedded in posts to ensure they are retained for future reference, as well as to be searchable. If you need to embed a large block of code, you can use Markdown formatting and put a triple-backtick ``` at the start and end of the code block.
If you want to extend the toolbox with additional links, just create a Pull Request in the public toolbox GitHub repository.