private boolean equals(Object left,Object right) {
            if (left==null && right==null) return true;
            if (left==null) return false;
            return left.equals(right);
        }
A condition which is true of the <i>values</i> of its two subconditions are true
and both have the same value

@author bratseth
container-search/src/main/java/com/yahoo/prelude/semantics/rule/ComparisonCondition.java