Mongodb 找不到能够从类型[java.util.LinkedHashMap<；？，？>；]转换为类型[java.lang.String]的转换器

我正在尝试在MongoDB中进行多组聚合

下面是我运行Spring引导代码时得到的异常

例外情况

org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.util.LinkedHashMap<?, ?>] to type [java.lang.String]
    at org.springframework.core.convert.support.GenericConversionService.handleConverterNotFound(GenericConversionService.java:322) ~[spring-core-5.3.4.jar:5.3.4]
    at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:195) ~[spring-core-5.3.4.jar:5.3.4]
    at org.springframework.core.convert.support.CollectionToStringConverter.convert(CollectionToStringConverter.java:70) ~[spring-core-5.3.4.jar:5.3.4]
    at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:41) ~[spring-core-5.3.4.jar:5.3.4]
    at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:192) ~[spring-core-5.3.4.jar:5.3.4]
    at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:175) ~[spring-core-5.3.4.jar:5.3.4]
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.getPotentiallyConvertedSimpleRead(MappingMongoConverter.java:1032) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readCollectionOrArray(MappingMongoConverter.java:1138) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readValue(MappingMongoConverter.java:1578) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter$MongoDbPropertyValueProvider.getPropertyValue(MappingMongoConverter.java:1478) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readProperties(MappingMongoConverter.java:450) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.populateProperties(MappingMongoConverter.java:367) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:347) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:317) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:250) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:246) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:98) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.MongoTemplate$ReadDocumentCallback.doWith(MongoTemplate.java:3160) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.MongoTemplate.lambda$null$24(MongoTemplate.java:2169) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at com.mongodb.client.internal.MappingIterable$1.accept(MappingIterable.java:62) ~[mongodb-driver-sync-4.1.1.jar:na]
    at com.mongodb.client.internal.MongoIterableImpl.forEach(MongoIterableImpl.java:123) ~[mongodb-driver-sync-4.1.1.jar:na]
    at com.mongodb.client.internal.MappingIterable.forEach(MappingIterable.java:59) ~[mongodb-driver-sync-4.1.1.jar:na]
    at com.mongodb.client.internal.MappingIterable.into(MappingIterable.java:69) ~[mongodb-driver-sync-4.1.1.jar:na]
    at org.springframework.data.mongodb.core.MongoTemplate.lambda$doAggregate$25(MongoTemplate.java:2172) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.MongoTemplate.execute(MongoTemplate.java:561) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.MongoTemplate.doAggregate(MongoTemplate.java:2129) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.MongoTemplate.aggregate(MongoTemplate.java:2098) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at org.springframework.data.mongodb.core.MongoTemplate.aggregate(MongoTemplate.java:1997) ~[spring-data-mongodb-3.1.5.jar:3.1.5]
    at com.lowes.pitstop.api.repository.AppDetailsRepository.fetchAppMapping(AppDetailsRepository.java:52) ~[classes/:na]
    at com.lowes.pitstop.api.repository.AppDetailsRepository$$FastClassBySpringCGLIB$$92a48211.invoke(<generated>) ~[classes/:na]
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) ~[spring-core-5.3.4.jar:5.3.4]
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:779) ~[spring-aop-5.3.4.jar:5.3.4]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.3.4.jar:5.3.4]
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750) ~[spring-aop-5.3.4.jar:5.3.4]
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:137) ~[spring-tx-5.3.4.jar:5.3.4]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.4.jar:5.3.4]
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750) ~[spring-aop-5.3.4.jar:5.3.4]
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:692) ~[spring-aop-5.3.4.jar:5.3.4]
    at com.lowes.pitstop.api.repository.AppDetailsRepository$$EnhancerBySpringCGLIB$$cb909013.fetchAppMapping(<generated>) ~[classes/:na]
    at com.lowes.pitstop.api.handler.AppDetailsHandler.getAppMapping(AppDetailsHandler.java:31) ~[classes/:na]
    at com.lowes.pitstop.api.controller.ApplicationDetailsController.getAppMapping(ApplicationDetailsController.java:47) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_201]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_201]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_201]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_201]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:197) ~[spring-web-5.3.4.jar:5.3.4]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:141) ~[spring-web-5.3.4.jar:5.3.4]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106) ~[spring-webmvc-5.3.4.jar:5.3.4]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:894) ~[spring-webmvc-5.3.4.jar:5.3.4]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.4.jar:5.3.4]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.4.jar:5.3.4]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1060) ~[spring-webmvc-5.3.4.jar:5.3.4]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:962) ~[spring-webmvc-5.3.4.jar:5.3.4]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.4.jar:5.3.4]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.4.jar:5.3.4]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:626) ~[tomcat-embed-core-9.0.43.jar:4.0.FR]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.4.jar:5.3.4]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:733) ~[tomcat-embed-core-9.0.43.jar:4.0.FR]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.4.jar:5.3.4]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.4.jar:5.3.4]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.4.jar:5.3.4]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.4.jar:5.3.4]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:93) ~[spring-boot-actuator-2.4.3.jar:2.4.3]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.4.jar:5.3.4]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.4.jar:5.3.4]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.4.jar:5.3.4]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:346) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:887) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1684) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_201]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_201]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_201]

当我运行这段代码时，我得到了上面的异常 Spring引导聚合器

GroupOperation apiGroup = Aggregation.group("department", "domain", "application").push(new BasicDBObject("apis", "$apis")).as("apis");
        
GroupOperation applicationGroup = Aggregation.group("_id.department", "_id.domain").push(new BasicDBObject("application", "$_id.application").append("apis", "$apis")).as("application");
        
GroupOperation domainGroup = Aggregation.group("_id.department").push(new BasicDBObject("domain", "$_id.domain").append("application", "$application")).as("domain");
        
GroupOperation departmentGroup = Aggregation.group("_id.department").push(new BasicDBObject("department", "$_id.department").append("domain", "$domain")).as("department");
        
Aggregation aggregation = Aggregation.newAggregation(apiGroup, applicationGroup, domainGroup, departmentGroup);
        
AggregationResults<Department> appMappingAggregate = operations.aggregate(aggregation, "applicationDetails", Department.class);

GroupOperation apiGroup = Aggregation.group("department", "domain", "application").push(new BasicDBObject("apis", "$apis")).as("apis");
        
GroupOperation applicationGroup = Aggregation.group("_id.department", "_id.domain").push(new BasicDBObject("application", "$_id.application").append("apis", "$apis")).as("application");
        
GroupOperation domainGroup = Aggregation.group("_id.department").push(new BasicDBObject("domain", "$_id.domain").append("application", "$application")).as("domain");
        
GroupOperation departmentGroup = Aggregation.group("_id.department").push(new BasicDBObject("department", "$_id.department").append("domain", "$domain")).as("department");
        
Aggregation aggregation = Aggregation.newAggregation(apiGroup, applicationGroup, domainGroup, departmentGroup);
        
AggregationResults<Department> appMappingAggregate = operations.aggregate(aggregation, "applicationDetails", Department.class);

private String department;
    private List<Domain> domain;

private String domain;
private List<Application> application;

private String application;
private List<API> apis;

private String api;
private String apiPath;
private String status;