Completion and resolving on second argument is working if first argument if "java".
Java methods completion
Binary/unary/etc. expression types are calculated if operands are appropriate java classes or literal expressions. The result parameters are always java classes (in case of literal operands - boxed types).
If resolve crashes
Sometimes you may get wrong result of the resolve - for example in long complex expressions. Yet it not work for standard functions - except createObject.
Then you may specify variable type in comments for completion to work for its methods. The pattern is (if you are familiar with regular expressions)
<!---[^@]*@cfmlvariable name=\"([^\"]+)\" type=\"([^\"]*)\"([^-]*|-[^-]|--[^-]|---[^>])*--->>
Well... it is easier to give an example =) Here is it: <!--- @cfmlvariable name="yourVariableName" type="javaClassName" --->
And your completion would be working from this comment down to next such comment for this variable. Of course resolve works on "type" parameter.