App Engine Datanucleus JPA throwing javax.persistence.PersistenceException on Collection properties of Entities

Question

The error occurs at runtime after the enhancement has been done successfully. I thought it had got to do with entity relationships but further probe showed that the exception is due to having a collection interface as a property in the entity. List will cause the exception but ArrayList won't. Set will but SortedSet won't. Please help me.

package model;

import java.util.ArrayList;
import java.util.List;

import javax.persistence.ElementCollection;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class Person {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;


    // @ElementCollection
    private List<String> name = new ArrayList<String>();
    private char gender;
    private int age;

    public Long getId() {
        return id;
    }

    public List<String> getName() {
        return name;
    }

    public char getGender() {
        return gender;
    }

    public int getAge() {
        return age;
    }

    public void setName(List<String> name) {
        this.name = name;
    }

    public void setGender(char gender) {
        this.gender = gender;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

        EntityManagerFactory emf = EMF.get();
        EntityManager em = null;

        try {
            em = emf.createEntityManager();
            Query query = em.createQuery("SELECT p FROM Person p");
            System.out.println("Got Here!!!");
            List<Person> persons = new ArrayList<Person>();
            persons = (List<Person>) query.getResultList();
            
        } finally {
            if (em != null)
                em.close();
        }

Stack Trace

[junitlauncher] Running test.web.HomePageTest
     [exec] 2022-05-07 09:41:35.005:WARN:oejs.HttpChannel:qtp1367165453-19: /Got Here!!!
     [exec]
     [exec] javax.persistence.PersistenceException: Class "model.Person" field "model.Person" : declared as a reference type (interface/Object) but no implementation classes of "java.util.List" have been found!
     [exec]     at org.datanucleus.api.jpa.NucleusJPAHelper.getJPAExceptionForNucleusException(NucleusJPAHelper.java:302)    
     [exec]     at org.datanucleus.api.jpa.JPAQuery.getResultList(JPAQuery.java:202)
     [exec]     at controller.MockController.doGet(Unknown Source)
     [exec]     at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
     [exec]     at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
     [exec]     at org.eclipse.jetty.servlet.ServletHolder$NotAsync.service(ServletHolder.java:1459)
     [exec]     at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:799)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$ChainEnd.doFilter(ServletHandler.java:1631)
     [exec]     at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:148)   
     [exec]     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
     [exec]     at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:46)
     [exec]     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
     [exec]     at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:74)
     [exec]     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
     [exec]     at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:62)   
     [exec]     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
     [exec]     at com.google.appengine.tools.development.jetty9.StaticFileFilter.doFilter(StaticFileFilter.java:138)        
     [exec]     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
     [exec]     at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectRequest(DevAppServerModulesFilter.java:377)
     [exec]     at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectModuleRequest(DevAppServerModulesFilter.java:360)
     [exec]     at com.google.appengine.tools.development.DevAppServerModulesFilter.doFilter(DevAppServerModulesFilter.java:127)
     [exec]     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
     [exec]     at com.google.appengine.tools.development.DevAppServerRequestLogFilter.doFilter(DevAppServerRequestLogFilter.java:44)
     [exec]     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:201)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:548)
     [exec]     at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
     [exec]     at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:571)
     [exec]     at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
     [exec]     at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235)
     [exec]     at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1624)
     [exec]     at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233)
     [exec]     at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1440)
     [exec]     at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:501)
     [exec]     at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1594)
     [exec]     at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186)
     [exec]     at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1355)
     [exec]     at com.google.appengine.tools.development.jetty9.DevAppEngineWebAppContext.doScope(DevAppEngineWebAppContext.java:109)
     [exec]     at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
     [exec]     at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
     [exec]     at com.google.appengine.tools.development.jetty9.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:613)
     [exec]     at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
     [exec]     at org.eclipse.jetty.server.Server.handle(Server.java:516)
     [exec]     at org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:487)
     [exec]     at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:732)
     [exec]     at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:479)
     [exec]     at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:277)
     [exec]     at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311)
     [exec]     at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:105)
     [exec]     at org.eclipse.jetty.io.ChannelEndPoint$1.run(ChannelEndPoint.java:104)
     [exec]     at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:883)
     [exec]     at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1034)
     [exec]     at java.base/java.lang.Thread.run(Thread.java:834)
     [exec] Caused by:
     [exec] org.datanucleus.metadata.InvalidMemberMetaDataException: Class "model.Person" field "model.Person" : declared as a reference type (interface/Object) but no implementation classes of "java.util.List" have been found!
     [exec]     at org.datanucleus.metadata.MetaDataUtils.getImplementationNamesForReferenceField(MetaDataUtils.java:549)    
     [exec]     at org.datanucleus.store.mapped.mapping.ReferenceMapping.createPerImplementationColumnsForReferenceField(ReferenceMapping.java:288)
     [exec]     at org.datanucleus.store.mapped.mapping.ReferenceMapping.prepareDatastoreMapping(ReferenceMapping.java:210)  
     [exec]     at org.datanucleus.store.mapped.mapping.ReferenceMapping.initialize(ReferenceMapping.java:106)
     [exec]     at org.datanucleus.store.mapped.mapping.InterfaceMapping.initialize(InterfaceMapping.java:52)
     [exec]     at org.datanucleus.store.mapped.mapping.MappingFactory.createMapping(MappingFactory.java:97)
     [exec]     at org.datanucleus.store.mapped.mapping.AbstractMappingManager.getMapping(AbstractMappingManager.java:263)   
     [exec]     at com.google.appengine.datanucleus.mapping.DatastoreTable.addFieldMapping(DatastoreTable.java:491)
     [exec]     at com.google.appengine.datanucleus.mapping.DatastoreTable.initializeNonPK(DatastoreTable.java:436)
     [exec]     at com.google.appengine.datanucleus.mapping.DatastoreTable.buildMapping(DatastoreTable.java:374)
     [exec]     at com.google.appengine.datanucleus.DatastoreManager.buildStoreData(DatastoreManager.java:439)
     [exec]     at com.google.appengine.datanucleus.DatastoreManager.newStoreData(DatastoreManager.java:403)
     [exec]     at org.datanucleus.store.AbstractStoreManager.addClasses(AbstractStoreManager.java:1183)
     [exec]     at org.datanucleus.store.AbstractStoreManager.addClass(AbstractStoreManager.java:1157)
     [exec]     at org.datanucleus.store.mapped.MappedStoreManager.getDatastoreClass(MappedStoreManager.java:407)
     [exec]     at com.google.appengine.datanucleus.DatastoreManager.getDatastoreClass(DatastoreManager.java:544)
     [exec]     at com.google.appengine.datanucleus.query.DatastoreQuery.compile(DatastoreQuery.java:234)
     [exec]     at com.google.appengine.datanucleus.query.JPQLQuery.performExecute(JPQLQuery.java:170)
     [exec]     at org.datanucleus.store.query.Query.executeQuery(Query.java:1789)
     [exec]     at org.datanucleus.store.query.Query.executeWithMap(Query.java:1693)
     [exec]     at org.datanucleus.api.jpa.JPAQuery.getResultList(JPAQuery.java:185)
     [exec]     at controller.MockController.doGet(Unknown Source)
     [exec]     at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
     [exec]     at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
     [exec]     at org.eclipse.jetty.servlet.ServletHolder$NotAsync.service(ServletHolder.java:1459)
     [exec]     at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:799)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$ChainEnd.doFilter(ServletHandler.java:1631)
     [exec]     at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:148)   
     [exec]     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
     [exec]     at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:46)
     [exec]     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
     [exec]     at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:74)
     [exec]     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
     [exec]     at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:62)   
     [exec]     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
     [exec]     at com.google.appengine.tools.development.jetty9.StaticFileFilter.doFilter(StaticFileFilter.java:138)        
     [exec]     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
     [exec]     at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectRequest(DevAppServerModulesFilter.java:377)
     [exec]     at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectModuleRequest(DevAppServerModulesFilter.java:360)
     [exec]     at com.google.appengine.tools.development.DevAppServerModulesFilter.doFilter(DevAppServerModulesFilter.java:127)
     [exec]     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
     [exec]     at com.google.appengine.tools.development.DevAppServerRequestLogFilter.doFilter(DevAppServerRequestLogFilter.java:44)
     [exec]     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:201)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:548)
     [exec]     at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
     [exec]     at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:571)
     [exec]     at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
     [exec]     at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235)
     [exec]     at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1624)
     [exec]     at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233)
     [exec]     at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1440)
     [exec]     at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188)
     [exec]     at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:501)
     [exec]     at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1594)
     [exec]     at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186)
     [exec]     at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1355)
     [exec]     at com.google.appengine.tools.development.jetty9.DevAppEngineWebAppContext.doScope(DevAppEngineWebAppContext.java:109)
     [exec]     at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
     [exec]     at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
     [exec]     at com.google.appengine.tools.development.jetty9.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:613)
     [exec]     at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
     [exec]     at org.eclipse.jetty.server.Server.handle(Server.java:516)
     [exec]     at org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:487)
     [exec]     at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:732)
     [exec]     at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:479)
     [exec]     at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:277)
     [exec]     at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311)
     [exec]     at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:105)
     [exec]     at org.eclipse.jetty.io.ChannelEndPoint$1.run(ChannelEndPoint.java:104)
     [exec]     at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:883)
     [exec]     at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1034)
     [exec]     at java.base/java.lang.Thread.run(Thread.java:834)

Dependencies

        <!-- https://mvnrepository.com/artifact/com.google.appengine.orm/datanucleus-appengine -->
        <dependency org="com.google.appengine.orm" name="datanucleus-appengine" rev="2.1.2" conf="compile->default;runtime->default" />

        <!-- https://mvnrepository.com/artifact/org.datanucleus/datanucleus-api-jpa -->
        <dependency org="org.datanucleus" name="datanucleus-api-jpa" rev="3.1.3" conf="compile->default;runtime->default" />
        
        <!-- https://mvnrepository.com/artifact/org.ow2.asm/asm -->
        <dependency org="org.ow2.asm" name="asm" rev="9.2" conf="compile->default;runtime->default" />