drools-eclipse/org.drools.eclipse/src/main/java/org/drools/eclipse/reteoo/AlphaNodeVertex.java
public String getEvaluator() {
        AlphaNodeFieldConstraint constraint = this.node.getConstraint();
        if (constraint instanceof MvelConstraint) {
        	MvelConstraint mvelConstraint = (MvelConstraint) constraint;
            return mvelConstraint.toString();
        }
        return null;
    }
public String getEvaluator() {
        AlphaNodeFieldConstraint constraint = this.node.getConstraint();
        if (constraint instanceof MvelConstraint) {
        	MvelConstraint mvelConstraint = (MvelConstraint) constraint;
            return mvelConstraint.toString();
        }
        return null;
    }
Constraint's evaluator string

@return evaluator string