MissingPropertyException when extending HttpServletRequestWrapper

[Erando89]

Task List

• Steps to reproduce provided
• Stacktrace (if present) provided
• Example that reproduces the problem uploaded to Github
• Full description of the issue provided (see below)

Steps to Reproduce

1. Download TestGrails3App-bug-report-08022019.zip
2. run-app
3. set debug Breakpoint at de.testapp.servletfilter.MyServletFilter#doFilter line 16
4. call http://localhost:8080/foo

Expected Behaviour

I have defined a ServletFilter (javax.servlet.Filter) which is defined in resources.groovy. In the doFilter() method I use the groovy DSL to set an attribute to the request object (HttpServletRequest):
httpReq.filter3 = "filter3-value"
This doesn't cause any problems. Then I use the request object to create a de.testapp.servletfilter.MyServletFilter.CleanServletRequest object which extends the HttpServletRequestWrapper. This class does nothing but extending its super class. After that I want to set another attribute to the request but this time I use the cleanRequest object since this will be the one I'm going to feed the filter chain with for further processing:
cleanRequest.setAttribute("filter1", "filter1-value")
No problems when using the setter setAttribute(). When I want to do this using groovy DSL though an groovy.lang.MissingPropertyException gets thrown:
cleanRequest.filter2 = "filter2-value" // throws exception!

Please note: This used to work in Grails 2.5.6.
I use this servlet filter to create a derived HttpServletRequestWrapper just like in my example. By overriding the getParameter() method I can process the parameters before handing them to the application layer.

Actual Behaviour

2019-02-08 14:31:23.432 ERROR --- [nio-8080-exec-9] .a.c.c.C.[.[.[.[grailsDispatcherServlet] : Servlet.service() for servlet [grailsDispatcherServlet] in context with path [] threw exception

groovy.lang.MissingPropertyException: No such property: filter2 for class: de.testapp.servletfilter.MyServletFilter
	at groovy.lang.MetaClassImpl.invokeStaticMissingProperty(MetaClassImpl.java:1014)
	at groovy.lang.MetaClassImpl.setProperty(MetaClassImpl.java:2749)
	at groovy.lang.MetaClassImpl.setProperty(MetaClassImpl.java:3785)
	at org.codehaus.groovy.runtime.InvokerHelper.setProperty(InvokerHelper.java:215)
	at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.setProperty(ScriptBytecodeAdapter.java:497)
	at de.testapp.servletfilter.MyServletFilter$CleanServletRequest.propertyMissing(MyServletFilter.groovy)
	at sun.reflect.GeneratedMethodAccessor255.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springsource.loaded.ri.ReflectiveInterceptor.jlrMethodInvoke(ReflectiveInterceptor.java:1427)
	at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:98)
	at groovy.lang.MetaClassImpl.invokeMissingProperty(MetaClassImpl.java:894)
	at groovy.lang.MetaClassImpl.setProperty(MetaClassImpl.java:2751)
	at groovy.lang.MetaClassImpl.setProperty(MetaClassImpl.java:3785)
	at de.testapp.servletfilter.MyServletFilter$CleanServletRequest.setProperty(MyServletFilter.groovy)
	at org.codehaus.groovy.runtime.InvokerHelper.setProperty(InvokerHelper.java:213)
	at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.setProperty(ScriptBytecodeAdapter.java:497)
	at de.testapp.servletfilter.MyServletFilter.doFilter(MyServletFilter.groovy:20)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:111)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.grails.web.servlet.mvc.GrailsWebRequestFilter.doFilterInternal(GrailsWebRequestFilter.java:77)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

Environment Information

• Operating System: any, in my case Windows 10 1809
• Grails Version: 3.3.9
• JDK Version: jdk8u202-b08-adoptopenjdk

Example Application

TestGrails3App-bug-report-08022019.zip

[jeffscottbrown]

You have this in your MyServletFilter class.

...
CleanServletRequest cleanRequest = new CleanServletRequest(httpReq)
cleanRequest.setAttribute("filter1", "filter1-value")
cleanRequest.filter2 = "filter2-value"
...

CleanServletRequest extends HttpServletRequestWrapper.

What is it that you expect cleanRequest.filter2 to evaluate to?

[jeffscottbrown]

I think I understand the intent now. At a glance it isn't clear to me why https://github.com/grails/grails-core/blob/2484f24b1eccce3b42a3b3a04ebe067dfdeb7be9/grails-web/src/main/groovy/org/grails/web/servlet/HttpServletRequestExtension.groovy#L59 isn't being applied there.