The following is the code from controller

        private final String URI_CUSTOMER_ID     = "/springframeworkandjwt-Customer/{id}";

        @GetMapping("/v1usingWebClient/{id}")
    @PreAuthorize("hasRole('ADMIN')")
    @Transactional
    public Mono<Customer> getCustomerUsingWebClient(@PathVariable final long id)
    {   
        LOGGER.info("came into ARL.");
    try {           
            LOGGER.info("before mutating...");
            WebClient webClient        = WebClient.create("http://localhost:8084");

                      webClient        = webClient.mutate().filters(filterList -> {
                                                 filterList.add(0, basicAuthentication("Sunil Manik Reddy", "12345678"));
                                                                             })
                                                 .build();
            LOGGER.info("before submitting request...");
            Customer customer          =  webClient.get().uri(URI_CUSTOMER_ID+id).accept(MediaType.APPLICATION_JSON)
                                                .retrieve()
                                                .bodyToMono(Customer.class)
                                                .block();

            LOGGER.info("before responding...");
            return Mono.just(customer);

        }catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

Configuration.java as follows:

package com.mycompany.appofCloud.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.web.reactive.function.client.WebClient;

@ComponentScan
public class Configuration{

    @Bean
    WebClient webClient(WebClient.Builder builder) {
        return builder.build();
    }
}

since WebClient needs a @Bean to annotate with.

Comment From: jmankari

Following is the error or exception thrown:

IncompatibleClassChangeError: class reactor.netty.http.client.HttpClientConfig overrides final method reactor.netty.transport.ClientTransportConfig.connectionProvider()Lreactor/netty/resources/ConnectionProvider;] with root cause
java.lang.IncompatibleClassChangeError: class reactor.netty.http.client.HttpClientConfig overrides final method reactor.netty.transport.ClientTransportConfig.connectionProvider()Lreactor/netty/resources/ConnectionProvider;
        at java.base/java.lang.ClassLoader.defineClass1(Native Method)
        at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1012)
        at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:150)
        at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:862)
        at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:760)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:681)
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:639)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
        at reactor.netty.http.client.HttpClient.create(HttpClient.java:398)
        at org.springframework.http.client.reactive.ReactorClientHttpConnector.<init>(ReactorClientHttpConnector.java:56)
        at org.springframework.web.reactive.function.client.DefaultWebClientBuilder.initConnector(DefaultWebClientBuilder.java:339)
        at org.springframework.web.reactive.function.client.DefaultWebClientBuilder.build(DefaultWebClientBuilder.java:311)
        at org.springframework.web.reactive.function.client.WebClient.create(WebClient.java:156)
        at com.mycompany.appofCloud.controller.AppController.getCustomerUsingWebClient(AppController.java:74)
        at com.mycompany.appofCloud.controller.AppController$$FastClassBySpringCGLIB$$bd02f952.invoke(<generated>)
        at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
        at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:771)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
        at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:749)
        at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:371)
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:134)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
        at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:749)
        at org.springframework.security.access.intercept.aopalliance.MethodSecurityInterceptor.invoke(MethodSecurityInterceptor.java:67)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
        at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:749)
        at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:691)
        at com.mycompany.appofCloud.controller.AppController$$EnhancerBySpringCGLIB$$a4695cf5.getCustomerUsingWebClient(<generated>)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:568)
        at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:197)
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:141)
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:893)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:807)
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1061)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:961)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:626)
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
        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:53)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:113)
        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$VirtualFilterChain.doFilter(FilterChainProxy.java:352)
        at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:117)
        at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
        at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:126)
        at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:120)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
        at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:131)
        at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:85)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
        at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:100)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
        at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:164)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
        at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
        at com.mycompany.appofCloud.security.jwt.AuthTokenFilter.doFilterInternal(AuthTokenFilter.java:49)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
        at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:107)
        at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:93)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
        at org.springframework.web.filter.CorsFilter.doFilterInternal(CorsFilter.java:91)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
        at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:90)
        at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:75)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
        at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:117)
        at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
        at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:62)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
        at org.springframework.security.web.session.DisableEncodeUrlFilter.doFilterInternal(DisableEncodeUrlFilter.java:42)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
        at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:225)
        at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:190)
        at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358)
        at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        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:202)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590)
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.base/java.lang.Thread.run(Thread.java:833)

Apr 21, 2024 3:51:00 PM org.springframework.core.log.LogFormatUtils traceDebug
FINE: "ERROR" dispatch for GET "/error", parameters={}
Apr 21, 2024 3:51:00 PM org.springframework.web.servlet.handler.AbstractHandlerMapping getHandler
FINE: Mapped to org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController#error(HttpServletRequest)
Apr 21, 2024 3:51:00 PM org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor writeWithMessageConverters
FINE: Using 'application/json', given [*/*] and supported [application/json, application/*+json, application/json, application/*+json]
Apr 21, 2024 3:51:00 PM org.springframework.core.log.LogFormatUtils traceDebug
FINE: Writing [{timestamp=Sun Apr 21 15:51:00 IST 2024, status=500, error=Internal Server Error, trace=java.lang.In (truncated)...

Comment From: wilkinsona

There's a problem with your application's classpath. It contains incompatible versions of reactor.netty.http.client.HttpClientConfig and reactor.netty.transport.ClientTransportConfig. This is out of Spring Boot's control.

If you need some help correcting the problem with your application's classpath and its dependencies, please follow up on Stack Overflow. As mentioned in the guidelines for contributing, we prefer to use GitHub issues only for bugs and enhancements.

Comment From: jmankari

Thanks buddy helped...