[rules-users] Null-safe traversal of nested sparse maps?

Dear fellow Droolers, [Sorry to repeat myself, but I thought this question might have gotten missed at the bottom of my other one.] One of my facts' properties, "attributes", is a Map of Map of String. Unfortunately the second level of keys is sparse. If the attribute I want is present, Fact(attributes.KeyOne.KeyTwo == 42) looks and works great. If KeyTwo is absent, however, I get org.drools.RuntimeDroolsException: Exception executing predicate attributes.KeyOne.KeyTwo == 42 [...] Caused by: [Error: unable to resolve method: java.util.HashMap.KeyTwo() [arglength=0]] [Near : {... Unknown ....}] The best syntax I've found which is null-safe is Fact(attributes.KeyOne["KeyTwo"] == 42) which works but hurts the eyes somewhat. I'm not clear whether MVEL-style null-safe traversal should work here; my experiments suggest it does not. Any suggestions? Thanks, -- | Dave Schweisguth http://schweisguth.org/~dave/ | | Home: dave at schweisguth.org Work: http://www.nileguide.com/ | | For compliance with the NJ Right to Know Act: Contents partially unknown |