Get NPE on deserializing values with recursive `@JsonIgnoreProperties`

[Romain-P]

I'm using spring-mvc for a restful service. By adding the dependency, my rest controllers automatically generate json from my response entities.

Dependency

jackson = '2.9.0'
compile "com.fasterxml.jackson.core:jackson-databind:$jackson"

Objects

@Getter @Setter
public final class UserDTO {
    [...]

    private Set<ActivityDTO> activities = Sets.newHashSet();
}


@Getter @Setter
public final class ActivityDTO {
    [...]

    private Set<ActivityDTO> subActivities;
}

Problem

Problems come in special cases. For example, I want to add an activity to an user. The following user-json works good, Jackson converts it without error.

{
"id": 1,
  "activities": [
    {
      "id": 1,
      "subActivities": null,
    }
  ]
}

But if I add an activity with sub activities, it crashes!

{
  "id": 6,
  "activities": [
    {
      "id": 19,
      "subActivities": [
        {
          "id": 20,
          "subActivities": [
            {
              "id": 24,
              "subActivities": null
            },
            {
              "id": 21,
              "subActivities": [
                {
                  "id": 23,
                  "subActivities": null
                },
                {
                  "id": 22,
                  "subActivities": null
                }
              ]
            }
          ]
        }
      ]
    }
  ]
}

Indeed, jackson can't deserialize this json and I don't understand why. I get the following error.. Any idea?

13:45:56.890 [http-nio-8080-exec-1] DEBUG org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod - Failed to resolve argument 0 of type 'com.ortec.gta.database.model.dto.UserDTO'
org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: (was java.lang.NullPointerException); nested exception is com.fasterxml.jackson.databind.JsonMappingException: (was java.lang.NullPointerException) (through reference chain: com.ortec.gta.database.model.dto.UserDTO["activities"]->java.util.HashSet[2]->com.ortec.gta.database.model.dto.ActivityDTO["subActivities"]->java.util.HashSet[0]->com.ortec.gta.database.model.dto.ActivityDTO["subActivities"])
	at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:238)
	at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:223)
	at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:201)
	at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.readWithMessageConverters(RequestResponseBodyMethodProcessor.java:150)
	at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:128)
	at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121)
	at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:158)
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:128)
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
	at org.springframework.web.servlet.FrameworkServlet.doPut(FrameworkServlet.java:883)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:664)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
	at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
	at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
	at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
	at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
	at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
	at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
	at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
	at org.springframework.security.oauth2.provider.authentication.OAuth2AuthenticationProcessingFilter.doFilter(OAuth2AuthenticationProcessingFilter.java:176)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
	at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
	at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:57)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
	at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
	at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
	at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
	at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
	at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
	at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at com.ortec.gta.configuration.ServletInitializer$CorsFilter.doFilter(ServletInitializer.java:78)
	at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
	at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:799)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1455)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)
Caused by: com.fasterxml.jackson.databind.JsonMappingException: (was java.lang.NullPointerException) (through reference chain: com.ortec.gta.database.model.dto.UserDTO["activities"]->java.util.HashSet[2]->com.ortec.gta.database.model.dto.ActivityDTO["subActivities"]->java.util.HashSet[0]->com.ortec.gta.database.model.dto.ActivityDTO["subActivities"])
	at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:391)
	at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:351)
	at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.wrapAndThrow(BeanDeserializerBase.java:1689)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:370)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:159)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:285)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:244)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:27)
	at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:127)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:368)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:159)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:285)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:244)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:27)
	at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:127)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:368)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:159)
	at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4001)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3072)
	at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:235)
	... 77 common frames omitted
Caused by: java.lang.NullPointerException: null
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:271)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:244)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:27)
	at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:127)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:368)
	... 93 common frames omitted

[Romain-P]

I had to rollback to 2.7.9. It seems this bug appeared since 2.8.0,
More details: https://stackoverflow.com/questions/45918309/jackson-get-a-null-reference-on-deserializing

[cowtowncoder]

I would need a full reproduction here: member in question is the value deserializer, which should not be null. But perhaps there is a custom deserializer that does not properly resolve value deserializer.
Regarding this, it would be helpful to indicate which Jackson modules are used (if any).
For example something like jackson-datatype-hibernate or jackson-datatype-guava would register additional deserializers for specific types of Collections.

Alternative some features like Object Id handling (@JsonIdentityInfo) could also invoke alternate handling and could be relevant. Or, unwrapping (@JsonUnwrapped) with recursion can actually cause problems similar to this.

Other than this I do not know of any existing problems that would manifest this way.

[cowtowncoder]

Can not reproduce. May be reopened with a reproduction.

[cen1]

@cowtowncoder I can also confirm this bug, exact same scenario as SO thread linked above. Specifically, @JsonIgnoreProperties with a combination of nested attributes (self-nesting of the same class) causes the NullPointer error mentioned above. Tested on jackson 2.9.5

This should be reopened.

Minimal test case:

public class JackBase {

    private String id;
}

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

import java.math.BigDecimal;
import java.util.List;

public class JackExt extends JackBase {

    private BigDecimal quantity;

    private String ignoreMe;

    @JsonIgnoreProperties({"ignoreMe"})
    private List<JackExt> linked;

    private List<KeyValue> metadata;

    public BigDecimal getQuantity() {
        return quantity;
    }

    public void setQuantity(BigDecimal quantity) {
        this.quantity = quantity;
    }

    public String getIgnoreMe() {
        return ignoreMe;
    }

    public void setIgnoreMe(String ignoreMe) {
        this.ignoreMe = ignoreMe;
    }

    public List<JackExt> getLinked() {
        return linked;
    }

    public void setLinked(List<JackExt> linked) {
        this.linked = linked;
    }

    public List<KeyValue> getMetadata() {
        return metadata;
    }

    public void setMetadata(List<KeyValue> metadata) {
        this.metadata = metadata;
    }
}

public class KeyValue {

    private String key;

    private String value;

    public String getKey() {
        return key;
    }

    public void setKey(String key) {
        this.key = key;
    }

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }

    public KeyValue(String key, String value) {
        this.key = key;
        this.value = value;
    }

    public KeyValue() {}
}

Input JSON:

{
	"id": "1",
	"quantity": 5,
	"ignoreMe": "yzx",
	"metadata": [
                {
                    "key": "position",
                    "value": "2"
                }
            ],
	"linked": [
		{
			"id": "1",
			"quantity": 5,
			"ignoreMe": "yzx",
			"metadata": [
                {
                    "key": "position",
                    "value": "2"
                }
            ]
		}
	]
}

Exception:

2018-06-05 19:07:48,911 ERROR  Rest Api error. com.fasterxml.jackson.databind.JsonMappingException: (was java.lang.NullPointerException) (through reference chain: JackExt["linked"]->java.util.ArrayList[0]->JackExt["metadata"])
	at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:391)
	at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:351)
	at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.wrapAndThrow(BeanDeserializerBase.java:1704)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:290)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:151)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:286)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:245)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:27)
	at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:127)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:288)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:151)
	at com.fasterxml.jackson.databind.ObjectReader._bind(ObjectReader.java:1574)
	at com.fasterxml.jackson.databind.ObjectReader.readValue(ObjectReader.java:965)
	at com.fasterxml.jackson.jaxrs.base.ProviderBase.readFrom(ProviderBase.java:815)
	at org.glassfish.jersey.message.internal.ReaderInterceptorExecutor$TerminalReaderInterceptor.invokeReadFrom(ReaderInterceptorExecutor.java:256)
	at org.glassfish.jersey.message.internal.ReaderInterceptorExecutor$TerminalReaderInterceptor.aroundReadFrom(ReaderInterceptorExecutor.java:235)
	at org.glassfish.jersey.message.internal.ReaderInterceptorExecutor.proceed(ReaderInterceptorExecutor.java:155)
	at org.glassfish.jersey.server.internal.MappableExceptionWrapperInterceptor.aroundReadFrom(MappableExceptionWrapperInterceptor.java:74)
	at org.glassfish.jersey.message.internal.ReaderInterceptorExecutor.proceed(ReaderInterceptorExecutor.java:155)
	at org.glassfish.jersey.message.internal.MessageBodyFactory.readFrom(MessageBodyFactory.java:1085)
	at org.glassfish.jersey.message.internal.InboundMessageContext.readEntity(InboundMessageContext.java:874)
	at org.glassfish.jersey.server.ContainerRequest.readEntity(ContainerRequest.java:271)
	at org.glassfish.jersey.server.internal.inject.EntityParamValueFactoryProvider$EntityValueFactory.provide(EntityParamValueFactoryProvider.java:96)
	at org.glassfish.jersey.server.spi.internal.ParamValueFactoryWithSource.provide(ParamValueFactoryWithSource.java:71)
	at org.glassfish.jersey.server.spi.internal.ParameterValueHelper.getParameterValues(ParameterValueHelper.java:94)
	at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$AbstractMethodParamInvoker.getParamValues(JavaResourceMethodDispatcherProvider.java:127)
	at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$ResponseOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:160)
	at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:99)
	at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:389)
	at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:347)
	at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:102)
	at org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:326)
	at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
	at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
	at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
	at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
	at org.glassfish.jersey.internal.Errors.process(Errors.java:267)
	at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317)
	at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305)
	at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154)
	at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473)
	at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427)
	at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388)
	at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341)
	at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228)
	at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:860)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650)
	at com.thetransactioncompany.cors.CORSFilter.doFilter(CORSFilter.java:209)
	at com.thetransactioncompany.cors.CORSFilter.doFilter(CORSFilter.java:244)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1629)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:533)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:190)
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1595)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:188)
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1253)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:168)
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:473)
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1564)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:166)
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1155)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
	at org.eclipse.jetty.server.Server.handle(Server.java:530)
	at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:347)
	at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:256)
	at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:279)
	at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:102)
	at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:124)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:247)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.produce(EatWhatYouKill.java:140)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:131)
	at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:382)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:708)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:626)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:272)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:245)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:27)
	at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:127)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:288)
	... 78 more

I can also confirm 2.7.9 works so this is a regression.

[cowtowncoder]

@cen1 Thank you for including reproduction. But I think it is missing couple of types (CommonItem and KeyValue); and also ObjectMapper configuration as private fields are not included by default. Could you include those so that reproduction can be run as a test?

[cen1]

Updated previus post with full test case. Commenting out @JsonIgnoreProperties stops the exception. Hopefully it's a trivial fix.

[cowtowncoder]

@cen1 Thanks! We'll see... it is problematic, being recursive self-reference, so may be simple, or might be next to impossible to tackle. Hope it's former :)

[cowtowncoder]

I am able to reproduce this. NPE itself is due to recursive definition that somehow either prevents contextualization, or leaves non-contextual instance to be used (createContextual() is where value deserializer is fetched, if not constructed from annotations earlier).

[cowtowncoder]

Oddly enough, commenting out metadata (or changing type, anything to avoid another List valued property) prevents problem.

[cen1]

Yes, this is how I actually encountered the problem, after adding another list in my project. This may or may not be connected to #1575 (which I also encountered in v2.8.10 but on a recursive non-list property).