I encountered this while working on: https://bugs.openjdk.org/browse/JMC-5641

The rule result buttons in the Results ui are not always expandable. This happens if the corresponding page's result group contains an underscore (e.g., garbage_collection, vm_operations, method_profiling, etc.).

This only occurs on the single page html created in RulesHtmlToolkit. `createRuleHtml` has an attribute uuid, which in the case of the larger html report is a string of unique numbers. In the case of the single page html, it is instead the topic of the rule (e.g., garbage_collection). The actual of the id is combined with the uuid to create a unique id for the rule result button in the html. The `toggleVisibility()` function in`rules_overview.html` matches the button id by splicing at the first index of an underscore in the id, so any button using an underscore as it's uuid in this case will be prematurely spliced and result in a null error trying to expand the rule result.