This option needs to be included in the Realm Configuration HOW-TO Common features section and possibly in the specific Realm Element attributes tables. Optionally, the API should be made clearer about the linkage between the server XML attributes and properties. This linkage is not obvious without a deep understanding of Tomcat internals. IMHO, the BaseRealm classes are designed for "public" consumption and the API docs should reflect that.
Patches are always welcome.
Correct the component
Fixed in 7.0.x and will be included in 7.0.20 onwards. Fixed in 6.0.x and will be included in 6.0.33 onwards. Fixed in 5.5.x and will be included in 5.5.34 onwards.