CXF 2.7.16: ClassFormatError: JVMCFRE114 field name is invalid; jaxws_asm

We upgrade CXF from v2.2.6 to v2.7.16. When we start IBM WebSphere Application Server v7.0.0.33 in Linux machine, error is reported for jaxws_asm/RetrieveRssFeedResponse:

Caused by: java.lang.ClassFormatError: JVMCFRE114 field name is invalid; class=com/abc/mobile/service/rss/jaxws_asm/RetrieveRssFeedResponse, offset=0
    at java.lang.ClassLoader.defineClassImpl(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:287)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:224)
    at org.apache.cxf.common.util.ASMHelper$TypeHelperClassLoader.defineClass(ASMHelper.java:367)
    at org.apache.cxf.common.util.ASMHelper.loadClass(ASMHelper.java:316)
    at org.apache.cxf.jaxws.WrapperClassGenerator.createWrapperClass(WrapperClassGenerator.java:229)

Here is our current understanding:

This error does not occur in local Windows machine WAS7.0.0.11
Class jaxws_asm.RetrieveRssFeedResponse does not exist at compile time. Instead, it's generated by CXF at runtime.
Our application code has Java package: com/abc/mobile/service/rss
Class WrapperClassGenerator in org.apache.cxf/cxf-bundle.jar/2.7.16 appends Java package “jaxws_asm” at line 160:

String pkg = new StringBuilder().append(getPackageName(method)).append(".jaxws_asm").append(anonymous ? "_an" : "").toString();
Our application code com.abc.mobile.service.rss.GlobalProductRssService.java has:

@WebMethod(operationName = "retrieveRssFeed")
Class WrapperClassGenerator in org.apache.cxf/cxf-bundle.jar/2.7.16 appends class name “Response” at line 164:

className = new StringBuilder().append(className).append("Response").toString();
We tried to add asm/asm.jar/3.3.1 to WEB-INF/lib or WAS7.0/java/jre/lib/ext. It did not help.
We have enabled class loading trace log by following IBM MustGather document: http://www-01.ibm.com/support/docview.wss?uid=swg21196187.

Trace log shows that "jaxws.RetrieveRssFeedResponse" is being loaded:

[1/5/16 11:39:04:447 EST] 00000014 CompoundClass >  loadClass com.abc.mobile.service.rss.jaxws.RetrieveRssFeedResponse this=com.ibm.ws.classloader.CompoundClassLoader@736d736d[PL][war:US-EAR/US.war] Entry
[1/5/16 11:39:04:447 EST] 00000014 CompoundClass >  loadClass com.abc.mobile.service.rss.jaxws.RetrieveRssFeedResponse this=com.ibm.ws.classloader.CompoundClassLoader@70207020[app:US-EAR] Entry
[1/5/16 11:39:04:448 EST] 00000014 CompoundClass <  loadClass com.abc.mobile.service.rss.jaxws.RetrieveRssFeedResponse failed Exit
[1/5/16 11:39:04:448 EST] 00000014 CompoundClass <  loadClass com.abc.mobile.service.rss.jaxws.RetrieveRssFeedResponse failed Exit

I have not found out why the above class loading trace log loads "jaxws.RetrieveRssFeedResponse". It's highly appreciated if anyone could share any clue about how to solve this ClassFormatError.

Solution

Thank you so much for your help. The issue has been solved by removing "[]" from @WebResult annotation. In other words, originally our application code has:

    @WebMethod(operationName = "retrieveRssFeed")
    @WebResult(name = "RssChannelDTO[]")

The error is solved by changing it to:

    @WebMethod(operationName = "retrieveRssFeed")
    @WebResult(name = "RssChannelDTO")

What we have done is:

Modify CXF/2.7.16/ASMHelper.java defineClass() method to print the dynamically generated classes. Totally 302 classes have been printed out.

        System.out.println("***********ASMHelper.TypeHelperClassLoader.defineClass(): " + name.replace('/', '.'));
        try {
            java.io.FileOutputStream fos = new java.io.FileOutputStream(name.replace('/', '.') + ".class");
            fos.write(bytes);
            fos.close();
        } catch (java.io.IOException ioe) {
            ioe.printStackTrace();
        }

Among all 302 generated classes, only RetrieveRssFeedResponse.class has "[]" in field name

        @XmlElement(name="RssChannelDTO[]")
        private RssChannelDTO[] RssChannelDTO[];

Modify CXF/2.7.16/ASMHelper.java to add main method (because constructor of inner class TypeHelperClassLoader is private) to call loader.defineClass() method

After running main method, error is reported:

        Exception in thread "main" java.lang.ClassFormatError: Illegal field name "RssChannelDTO[]" in class RetrieveRssFeedResponse
            at java.lang.ClassLoader.defineClass1(Native Method)
            at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
            at java.lang.ClassLoader.defineClass(ClassLoader.java:642)
            at org.apache.cxf.common.util.ASMHelper$TypeHelperClassLoader.defineClass(ASMHelper.java:377)
            at org.apache.cxf.common.util.ASMHelper.main(ASMHelper.java:513)

Then we modified our application code to remove "[]" from @WebResult annotation. The generated RetrieveRssFeedResponse.class has:
```
        @XmlElement(name="RssChannelDTO")
        private RssChannelDTO[] RssChannelDTO;
```

Now error is gone and our WebSphere Application Server v7.0 can be started without any error.

Regarding the IBM class loading trace log shows only "jaxws.RetrieveRssFeedResponse", I guess the situation is:

IBM logging statement might ignore "_" and anything after it during logging
But IBM class loader can still load "jaxws_asm.RetrieveRssFeedResponse"

Anyway, this is only my guess and I have not checked any IBM source code.