Class BooleanClosureForMapPredicate<K,V> 
java.lang.Object
org.codehaus.groovy.runtime.callsite.BooleanClosureForMapPredicate<K,V> 
Helper class for internal use only.
 This creates a Predicate by calling a 
Closure and converting the result to a boolean.
 BooleanReturningMethodInvoker is used for caching.