[BUG] AppConfigurationRefresh.refreshConfigurations() inconsistency

[yanivnahoum]

Describe the bug
AppConfiguration for spring boot 2.7.x and 3.x behave inconsistently, and both seem wrong.
com.azure.spring:spring-cloud-azure-appconfiguration-config
In the 4.11.0 version (for Spring Boot 2.7.x), the method com.azure.spring.cloud.appconfiguration.config.AppConfigurationRefresh#refreshConfigurations is annotated with @Async, although it returns a type which is unsupported by Spring for @Async methods: Mono<T>
Effectively, it runs on a background thread just fine, but will throw a NPE if you try to obtain the returned boolean by calling Mono::block() or by assembling it in a reactive chain. When using Spring WebFlux - this is mandatory since the auto-refresh is not activated (it's for Spring MVC apps only).
In the 5.5.0 version (for Spring Boot 3.x), the method com.azure.spring.cloud.appconfiguration.config.AppConfigurationRefresh#refreshConfigurations is no longer annotated with @Async. So now it simply runs on the web worker thread synchronously, which I don't believe was the original intent.

Exception or Stack Trace
13:56:52.925 ERROR http-nio-8080-exec-1 o.a.c.c.C.[.[.[.[dispatcherServlet] Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException: Cannot invoke "reactor.core.publisher.Mono.block()" because the return value of "com.azure.spring.cloud.appconfiguration.config.AppConfigurationRefresh.refreshConfigurations()" is null] with root cause
java.lang.NullPointerException: Cannot invoke "reactor.core.publisher.Mono.block()" because the return value of "com.azure.spring.cloud.appconfiguration.config.AppConfigurationRefresh.refreshConfigurations()" is null
at com.att.training.springboot.examples.FeatureController.fetchAll(FeatureController.java:32)
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:205)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1072)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:965)
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:529)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:209)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:96)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:168)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:481)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:130)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:390)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:926)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1790)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)
at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.base/java.lang.Thread.run(Thread.java:833)

To Reproduce
Inject a com.azure.spring.cloud.appconfiguration.config.AppConfigurationRefresh into a Spring controller and call
appConfigurationRefresh.refreshConfigurations().block() in one of its methods.

Expected behavior
I would expect refreshConfigurations to run non blocking, async io using a reactive web client. That would allow us to keep the Mono signature, and make it usable both for Spring MVC apps and for Spring WebFlux apps.
I know there are other gaps to fill for Spring WebFlux, but at least this basic functionality would work as expected.

Screenshots
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Setup (please complete the following information):

• OS: macOS Ventura
• IDE: Intellij
• Library/Libraries: com.azure.spring:spring-cloud-azure-appconfiguration-config 4.11.0 & 5.5.0
• Java version: 17
• Frameworks: Spring Boot 2.7.14 / 3.1.2

Additional context
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Information Checklist
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• Bug Description Added
• Repro Steps Added
• Setup information Added

[Netyyyy]

@mrm9084 Please take a look

[mrm9084]

This should be a dup of this #35845. Looking into updating both libraries to fix the issue.

[yanivnahoum]

Hi @mrm9084, any progress with this?

[yanivnahoum]

Almost a year later, version 4.19.0 still has the same bug:

@Async
Mono<Boolean> refreshConfigurations();

Any plans to fix this?