无法在LHS中使用严格模式枚举来解决方法

Question

我正在使用Drools 5.4 我有时会遇到错误 引起：org.mvel2.CompileException：[错误：无法使用strict-mode解析方法：com.model.SPurpose.APurpose（）]     [近：{...目的== APurpose.S_ELIG ....}]

here is my classes

package com.model
public class SPurpose {

    private APurpose purpose;

    public SPurpose(APurpose purpose){

        this.setPurpose(purpose);
    }

    public APurpose getPurpose() {
        return purpose;
    }

    public void setPurpose(APurpose purpose) {
        this.purpose = purpose;
    }

}

package com.setup.model
public enum APurpose {
    P_ELIG,
    S_ELIG,
    E_CALC,
    S_VEST;

    public String value() {
        return name();
    }
    public static APurpose fromValue(String v) {
        return valueOf(v);
    }
}
I am using the DRL file
file name is service.drl
rule "calculate Elig"

when
    SPurpose(purpose == APurpose.S_ELIG)
    SMethod(sMethod == sMethod.HCOUNTING)

 then
    insert(new Hours()); 
 end;
 import java.util.Date;
import java.util.List;

import org.drools.KnowledgeBase;
import org.drools.runtime.StatefulKnowledgeSession;
import org.drools.runtime.rule.Row;
import org.drools.runtime.rule.ViewChangedEventListener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.model.SPurpose;
import com.setup.model.APurpose;

class ServiceImpl implements Service {

    private static final Logger logger = LoggerFactory
            .getLogger(ServiceImpl.class);

    ServiceCalculationServiceImpl(
            final KnowledgeBase kbase) {
        this.kbase = kbase;
    }
    private static final Resource[] resources = {
        new ClassPathResource("com/rules/service.drl"),
        new ClassPathResource("com/rules/break.drl")};
    public void calculateService(final Input input,
            final Output output) throws ServiceCalculationException {

       {
            KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
        for (Resource resource : resources) {`enter code here`
            kbuilder.add(resource, ResourceType.DRL);
            if (kbuilder.hasErrors()) {
                String s = kbuilder.getErrors().toString();
                throw new IllegalStateException(s);
            }
        }
        kbase = kbuilder.newKnowledgeBase();
            StatefulKnowledgeSession ksession = kbase
                    .newStatefulKnowledgeSession();

            ksession.insert(input);
            ksession.insert(new SMethod(input.getSMethod()));
            ksession.insert(new SPurpose(input.getPurpose()));// Adding the purpose
            ksession.insert(output);
            ksession.fireAllRules();
            ksession.dispose();

        }
}

any advice on it