java - Problems with hibernate and Spring boot -

i'm developing sample of api spring boot, , ok until put nested objects in classes. first have class named 'product' this.

@entity @table(name = "products") public class product extends baseentity {     @column(name = "description")    private string description;     @manytoone(fetch = fetchtype.eager)    @joincolumn(name="category_id")    @jsonmanagedreference    private category category;     public category getcategory() {        return category;    }     public void setcategory(category category) {        this.category = category;    }     // others getters , setters } 

and follow 'category' class

   @entity    @table(name="categories")    public class category extends baseentity{      @column(name = "description")    private string description;     @jsonignore    @onetomany(fetch = fetchtype.lazy, cascade = all, mappedby =                "category", targetentity = product.class)    private list<product> products;     public category() {       super();    }     public category(string name, date created, date lastupdate, string                     description, user user, list<product> products) {        super(name, created, lastupdate, user);        this.description = description;        this.products = products;    }     public list<product> getproducts() {       return products;    }     public void setproducts(list<product> products) {       this.products = products;    }     // others getters , setters } 

and stack when make request endpoint '/products'

java.lang.illegalargumentexception: can not set com.stock4newbies.models.category field com.stock4newbies.models.product.category com.stock4newbies.models.product @ sun.reflect.unsafefieldaccessorimpl.throwsetillegalargumentexception(unsafefieldaccessorimpl.java:167) ~[na:1.8.0_144] @ sun.reflect.unsafefieldaccessorimpl.throwsetillegalargumentexception(unsafefieldaccessorimpl.java:171) ~[na:1.8.0_144] @ sun.reflect.unsafeobjectfieldaccessorimpl.set(unsafeobjectfieldaccessorimpl.java:81) ~[na:1.8.0_144] @ java.lang.reflect.field.set(field.java:764) ~[na:1.8.0_144] @ org.hibernate.property.access.spi.setterfieldimpl.set(setterfieldimpl.java:38) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.tuple.entity.abstractentitytuplizer.setpropertyvalues(abstractentitytuplizer.java:612) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.tuple.entity.pojoentitytuplizer.setpropertyvalues(pojoentitytuplizer.java:220) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.persister.entity.abstractentitypersister.setpropertyvalues(abstractentitypersister.java:4647) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.engine.internal.twophaseload.doinitializeentity(twophaseload.java:172) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.engine.internal.twophaseload.initializeentity(twophaseload.java:128) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.loader.loader.initializeentitiesandcollections(loader.java:1133) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.loader.loader.processresultset(loader.java:992) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.loader.loader.doquery(loader.java:930) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.loader.loader.doqueryandinitializenonlazycollections(loader.java:336) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.loader.loader.dolist(loader.java:2617) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.loader.loader.dolist(loader.java:2600) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.loader.loader.listignorequerycache(loader.java:2429) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.loader.loader.list(loader.java:2424) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.loader.hql.queryloader.list(queryloader.java:501) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.hql.internal.ast.querytranslatorimpl.list(querytranslatorimpl.java:371) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.engine.query.spi.hqlqueryplan.performlist(hqlqueryplan.java:216) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.internal.sessionimpl.list(sessionimpl.java:1326) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.internal.queryimpl.list(queryimpl.java:87) ~[hibernate-core-5.0.12.final.jar:5.0.12.final] @ org.hibernate.jpa.internal.queryimpl.list(queryimpl.java:606) ~[hibernate-entitymanager-5.0.12.final.jar:5.0.12.final] @ org.hibernate.jpa.internal.queryimpl.getresultlist(queryimpl.java:483) ~[hibernate-entitymanager-5.0.12.final.jar:5.0.12.final] @ org.hibernate.jpa.criteria.compile.criteriaquerytypequeryadapter.getresultlist(criteriaquerytypequeryadapter.java:50) ~[hibernate-entitymanager-5.0.12.final.jar:5.0.12.final] @ org.springframework.data.jpa.repository.support.simplejparepository.findall(simplejparepository.java:329) ~[spring-data-jpa-1.11.6.release.jar:na] @ sun.reflect.nativemethodaccessorimpl.invoke0(native method) ~[na:1.8.0_144] @ sun.reflect.nativemethodaccessorimpl.invoke(nativemethodaccessorimpl.java:62) ~[na:1.8.0_144] @ sun.reflect.delegatingmethodaccessorimpl.invoke(delegatingmethodaccessorimpl.java:43) ~[na:1.8.0_144] @ java.lang.reflect.method.invoke(method.java:498) ~[na:1.8.0_144] @ org.springframework.data.repository.core.support.repositoryfactorysupport$queryexecutormethodinterceptor.executemethodon(repositoryfactorysupport.java:504) ~[spring-data-commons-1.13.6.release.jar:na] @ org.springframework.data.repository.core.support.repositoryfactorysupport$queryexecutormethodinterceptor.doinvoke(repositoryfactorysupport.java:489) ~[spring-data-commons-1.13.6.release.jar:na] @ org.springframework.data.repository.core.support.repositoryfactorysupport$queryexecutormethodinterceptor.invoke(repositoryfactorysupport.java:461) ~[spring-data-commons-1.13.6.release.jar:na] @ org.springframework.aop.framework.reflectivemethodinvocation.proceed(reflectivemethodinvocation.java:179) ~[spring-aop-4.3.10.release.jar:4.3.10.release] @ org.springframework.data.projection.defaultmethodinvokingmethodinterceptor.invoke(defaultmethodinvokingmethodinterceptor.java:56) ~[spring-data-commons-1.13.6.release.jar:na] @ org.springframework.aop.framework.reflectivemethodinvocation.proceed(reflectivemethodinvocation.java:179) ~[spring-aop-4.3.10.release.jar:4.3.10.release] @ org.springframework.transaction.interceptor.transactioninterceptor$1.proceedwithinvocation(transactioninterceptor.java:99) ~[spring-tx-4.3.10.release.jar:4.3.10.release] @ org.springframework.transaction.interceptor.transactionaspectsupport.invokewithintransaction(transactionaspectsupport.java:282) ~[spring-tx-4.3.10.release.jar:4.3.10.release] @ org.springframework.transaction.interceptor.transactioninterceptor.invoke(transactioninterceptor.java:96) ~[spring-tx-4.3.10.release.jar:4.3.10.release] @ org.springframework.aop.framework.reflectivemethodinvocation.proceed(reflectivemethodinvocation.java:179) ~[spring-aop-4.3.10.release.jar:4.3.10.release] @ org.springframework.dao.support.persistenceexceptiontranslationinterceptor.invoke(persistenceexceptiontranslationinterceptor.java:136) ~[spring-tx-4.3.10.release.jar:4.3.10.release] @ org.springframework.aop.framework.reflectivemethodinvocation.proceed(reflectivemethodinvocation.java:179) ~[spring-aop-4.3.10.release.jar:4.3.10.release] @ org.springframework.data.jpa.repository.support.crudmethodmetadatapostprocessor$crudmethodmetadatapopulatingmethodinterceptor.invoke(crudmethodmetadatapostprocessor.java:133) ~[spring-data-jpa-1.11.6.release.jar:na] @ org.springframework.aop.framework.reflectivemethodinvocation.proceed(reflectivemethodinvocation.java:179) ~[spring-aop-4.3.10.release.jar:4.3.10.release] @ org.springframework.aop.interceptor.exposeinvocationinterceptor.invoke(exposeinvocationinterceptor.java:92) ~[spring-aop-4.3.10.release.jar:4.3.10.release] @ org.springframework.aop.framework.reflectivemethodinvocation.proceed(reflectivemethodinvocation.java:179) ~[spring-aop-4.3.10.release.jar:4.3.10.release] @ org.springframework.data.repository.core.support.surroundingtransactiondetectormethodinterceptor.invoke(surroundingtransactiondetectormethodinterceptor.java:57) ~[spring-data-commons-1.13.6.release.jar:na] @ org.springframework.aop.framework.reflectivemethodinvocation.proceed(reflectivemethodinvocation.java:179) ~[spring-aop-4.3.10.release.jar:4.3.10.release] @ org.springframework.aop.framework.jdkdynamicaopproxy.invoke(jdkdynamicaopproxy.java:213) ~[spring-aop-4.3.10.release.jar:4.3.10.release] @ com.sun.proxy.$proxy107.findall(unknown source) ~[na:na] @ com.stock4newbies.services.productserviceimpl.findall(productserviceimpl.java:27) ~[classes/:na] @ com.stock4newbies.controllers.productcontroller.list(productcontroller.java:31) ~[classes/:na] @ sun.reflect.nativemethodaccessorimpl.invoke0(native method) ~[na:1.8.0_144] @ sun.reflect.nativemethodaccessorimpl.invoke(nativemethodaccessorimpl.java:62) ~[na:1.8.0_144] @ sun.reflect.delegatingmethodaccessorimpl.invoke(delegatingmethodaccessorimpl.java:43) ~[na:1.8.0_144] @ java.lang.reflect.method.invoke(method.java:498) ~[na:1.8.0_144] @ org.springframework.web.method.support.invocablehandlermethod.doinvoke(invocablehandlermethod.java:205) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.springframework.web.method.support.invocablehandlermethod.invokeforrequest(invocablehandlermethod.java:133) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.springframework.web.servlet.mvc.method.annotation.servletinvocablehandlermethod.invokeandhandle(servletinvocablehandlermethod.java:97) ~[spring-webmvc-4.3.10.release.jar:4.3.10.release] @ org.springframework.web.servlet.mvc.method.annotation.requestmappinghandleradapter.invokehandlermethod(requestmappinghandleradapter.java:827) ~[spring-webmvc-4.3.10.release.jar:4.3.10.release] @ org.springframework.web.servlet.mvc.method.annotation.requestmappinghandleradapter.handleinternal(requestmappinghandleradapter.java:738) ~[spring-webmvc-4.3.10.release.jar:4.3.10.release] @ org.springframework.web.servlet.mvc.method.abstracthandlermethodadapter.handle(abstracthandlermethodadapter.java:85) ~[spring-webmvc-4.3.10.release.jar:4.3.10.release] @ org.springframework.web.servlet.dispatcherservlet.dodispatch(dispatcherservlet.java:967) ~[spring-webmvc-4.3.10.release.jar:4.3.10.release] @ org.springframework.web.servlet.dispatcherservlet.doservice(dispatcherservlet.java:901) ~[spring-webmvc-4.3.10.release.jar:4.3.10.release] @ org.springframework.web.servlet.frameworkservlet.processrequest(frameworkservlet.java:970) ~[spring-webmvc-4.3.10.release.jar:4.3.10.release] @ org.springframework.web.servlet.frameworkservlet.doget(frameworkservlet.java:861) ~[spring-webmvc-4.3.10.release.jar:4.3.10.release] @ javax.servlet.http.httpservlet.service(httpservlet.java:635) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.springframework.web.servlet.frameworkservlet.service(frameworkservlet.java:846) ~[spring-webmvc-4.3.10.release.jar:4.3.10.release] @ javax.servlet.http.httpservlet.service(httpservlet.java:742) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.core.applicationfilterchain.internaldofilter(applicationfilterchain.java:231) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.core.applicationfilterchain.dofilter(applicationfilterchain.java:166) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.tomcat.websocket.server.wsfilter.dofilter(wsfilter.java:52) ~[tomcat-embed-websocket-8.5.16.jar:8.5.16] @ org.apache.catalina.core.applicationfilterchain.internaldofilter(applicationfilterchain.java:193) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.core.applicationfilterchain.dofilter(applicationfilterchain.java:166) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.springframework.web.filter.onceperrequestfilter.dofilter(onceperrequestfilter.java:101) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.apache.catalina.core.applicationfilterchain.internaldofilter(applicationfilterchain.java:193) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.core.applicationfilterchain.dofilter(applicationfilterchain.java:166) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.springframework.security.web.filterchainproxy$virtualfilterchain.dofilter(filterchainproxy.java:317) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.access.intercept.filtersecurityinterceptor.invoke(filtersecurityinterceptor.java:127) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.access.intercept.filtersecurityinterceptor.dofilter(filtersecurityinterceptor.java:91) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.filterchainproxy$virtualfilterchain.dofilter(filterchainproxy.java:331) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.access.exceptiontranslationfilter.dofilter(exceptiontranslationfilter.java:114) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.filterchainproxy$virtualfilterchain.dofilter(filterchainproxy.java:331) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.session.sessionmanagementfilter.dofilter(sessionmanagementfilter.java:137) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.filterchainproxy$virtualfilterchain.dofilter(filterchainproxy.java:331) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.authentication.anonymousauthenticationfilter.dofilter(anonymousauthenticationfilter.java:111) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.filterchainproxy$virtualfilterchain.dofilter(filterchainproxy.java:331) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.servletapi.securitycontextholderawarerequestfilter.dofilter(securitycontextholderawarerequestfilter.java:170) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.filterchainproxy$virtualfilterchain.dofilter(filterchainproxy.java:331) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.savedrequest.requestcacheawarefilter.dofilter(requestcacheawarefilter.java:63) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.filterchainproxy$virtualfilterchain.dofilter(filterchainproxy.java:331) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ com.stock4newbies.security.jwtauthenticationtokenfilter.dofilterinternal(jwtauthenticationtokenfilter.java:51) ~[classes/:na] @ org.springframework.web.filter.onceperrequestfilter.dofilter(onceperrequestfilter.java:107) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.springframework.security.web.filterchainproxy$virtualfilterchain.dofilter(filterchainproxy.java:331) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.authentication.logout.logoutfilter.dofilter(logoutfilter.java:116) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.filterchainproxy$virtualfilterchain.dofilter(filterchainproxy.java:331) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.header.headerwriterfilter.dofilterinternal(headerwriterfilter.java:64) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.web.filter.onceperrequestfilter.dofilter(onceperrequestfilter.java:107) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.springframework.security.web.filterchainproxy$virtualfilterchain.dofilter(filterchainproxy.java:331) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.context.securitycontextpersistencefilter.dofilter(securitycontextpersistencefilter.java:105) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.filterchainproxy$virtualfilterchain.dofilter(filterchainproxy.java:331) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.context.request.async.webasyncmanagerintegrationfilter.dofilterinternal(webasyncmanagerintegrationfilter.java:56) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.web.filter.onceperrequestfilter.dofilter(onceperrequestfilter.java:107) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.springframework.security.web.filterchainproxy$virtualfilterchain.dofilter(filterchainproxy.java:331) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.filterchainproxy.dofilterinternal(filterchainproxy.java:214) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.security.web.filterchainproxy.dofilter(filterchainproxy.java:177) ~[spring-security-web-4.2.3.release.jar:4.2.3.release] @ org.springframework.web.filter.delegatingfilterproxy.invokedelegate(delegatingfilterproxy.java:346) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.springframework.web.filter.delegatingfilterproxy.dofilter(delegatingfilterproxy.java:262) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.apache.catalina.core.applicationfilterchain.internaldofilter(applicationfilterchain.java:193) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.core.applicationfilterchain.dofilter(applicationfilterchain.java:166) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.springframework.web.filter.requestcontextfilter.dofilterinternal(requestcontextfilter.java:99) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.springframework.web.filter.onceperrequestfilter.dofilter(onceperrequestfilter.java:107) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.apache.catalina.core.applicationfilterchain.internaldofilter(applicationfilterchain.java:193) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.core.applicationfilterchain.dofilter(applicationfilterchain.java:166) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.springframework.web.filter.httpputformcontentfilter.dofilterinternal(httpputformcontentfilter.java:105) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.springframework.web.filter.onceperrequestfilter.dofilter(onceperrequestfilter.java:107) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.apache.catalina.core.applicationfilterchain.internaldofilter(applicationfilterchain.java:193) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.core.applicationfilterchain.dofilter(applicationfilterchain.java:166) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.springframework.web.filter.hiddenhttpmethodfilter.dofilterinternal(hiddenhttpmethodfilter.java:81) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.springframework.web.filter.onceperrequestfilter.dofilter(onceperrequestfilter.java:107) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.apache.catalina.core.applicationfilterchain.internaldofilter(applicationfilterchain.java:193) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.core.applicationfilterchain.dofilter(applicationfilterchain.java:166) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.springframework.web.filter.characterencodingfilter.dofilterinternal(characterencodingfilter.java:197) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.springframework.web.filter.onceperrequestfilter.dofilter(onceperrequestfilter.java:107) ~[spring-web-4.3.10.release.jar:4.3.10.release] @ org.apache.catalina.core.applicationfilterchain.internaldofilter(applicationfilterchain.java:193) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.core.applicationfilterchain.dofilter(applicationfilterchain.java:166) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.core.standardwrappervalve.invoke(standardwrappervalve.java:198) ~[tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.core.standardcontextvalve.invoke(standardcontextvalve.java:96) [tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.authenticator.authenticatorbase.invoke(authenticatorbase.java:478) [tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.core.standardhostvalve.invoke(standardhostvalve.java:140) [tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.valves.errorreportvalve.invoke(errorreportvalve.java:80) [tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.core.standardenginevalve.invoke(standardenginevalve.java:87) [tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.catalina.connector.coyoteadapter.service(coyoteadapter.java:342) [tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.coyote.http11.http11processor.service(http11processor.java:799) [tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.coyote.abstractprocessorlight.process(abstractprocessorlight.java:66) [tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.coyote.abstractprotocol$connectionhandler.process(abstractprotocol.java:868) [tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.tomcat.util.net.nioendpoint$socketprocessor.dorun(nioendpoint.java:1455) [tomcat-embed-core-8.5.16.jar:8.5.16] @ org.apache.tomcat.util.net.socketprocessorbase.run(socketprocessorbase.java:49) [tomcat-embed-core-8.5.16.jar:8.5.16] @ java.util.concurrent.threadpoolexecutor.runworker(threadpoolexecutor.java:1149) [na:1.8.0_144] @ java.util.concurrent.threadpoolexecutor$worker.run(threadpoolexecutor.java:624) [na:1.8.0_144] @ org.apache.tomcat.util.threads.taskthread$wrappingrunnable.run(taskthread.java:61) [tomcat-embed-core-8.5.16.jar:8.5.16] @ java.lang.thread.run(thread.java:748) [na:1.8.0_144] 

i searched questions here , found approaches similar scenario none of solutions worked me, have idea being cause exception.

do not have @id fields in @entity classes? because if don't, absolutely have create them.

since you're working spring, should add spring-data-jpa project , using that, create following interface:

import org.springframework.data.repository.crudrepository; import org.springframework.stereotype.repository;  @repository public interface productrepository extends crudrepository<product, long> { } 

here assume, product entity has @id annotated field of type long.

and modify @restcontroller class:

    private productrepository productrepository;  **constructor**(productrepository pr){     productrepository = pr; }  @getmapping("/products")     public list<product> getproducts() {         list<product> products = new arraylist<>();         productrepository.findall().foreach(product -> products.add(product));         return products;     } 

p.s. should create getter or setters if call them. jpa not use since specified field access type. lookup 2.3 of jpa 2.1 specification. also, lot of annotation attributes specified redundant since match default values.