Build a Rest API in Spring (Versioning Error)

I see this error when I applied the 'If-None-Match' header value in PostMan. It happens in both examples discussed in Video (0 and 1).

Any idea what could be the cause?

Thanks

java.lang.IllegalArgumentException: Could not parse header 'If-None-Match' with value '0' org.springframework.http.HttpHeaders.getETagValuesAsList(HttpHeaders.java:1090) org.springframework.http.HttpHeaders.getIfNoneMatch(HttpHeaders.java:843) org.springframework.data.rest.webmvc.RepositoryEntityController.getItemResource(RepositoryEntityController.java:349) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) java.lang.reflect.Method.invoke(Method.java:497) org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221) org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:114) org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963) org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897) org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) javax.servlet.http.HttpServlet.service(HttpServlet.java:622) org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) javax.servlet.http.HttpServlet.service(HttpServlet.java:729) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87) org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) note The full stack trace of the root cause is available in the Apache Tomcat/8.5.4 logs.