Attachments fail using JAAS SSO container authentication

I'm trying to implement JSPWiki in a JAAS authentication
SSO environment. I have installed JSPWiki and made some
minor adjustments to the jspwiki.policy to account for
different user role names, and everything seems to be
working OK, except for one thing. None of the users
(including the administrator) can add attachments to
any of the pages. If I run the wiki standalone, (outside
JAAS), attachments work fine.

I'm using JSPWiki 2.10.1 with Tomcat 7.0.42 on a CentOS
6.5 server. My attachment test file is a one-line 32 byte text file.

I have three basic user roles, all require JAAS authorization
to access the wiki. User roles are admin, approved (read
and write for most pages), and unapproved (read only).

I'm fairly confident that the authentication methods are
working properly as all page permissions are working as
expected for each user type.

But when any admin or approved user tries to add an
attachment to any page, they get redirected to an Error.jsp
page showing a java.lang.Exception. To try and track down
the error source, I rewrote the AttachmentServlet class
and added a number of additional debug messages.

Based on what I'm seeing, it appears to me that the error
is caused by the upload.parseRequest ( req ) returning
an empty List<FileItem> fileItems in the upload method.

I added a debug line to verify the contents of the request
and it is properly populated entering the upload method,
but it is consumed @ req.getParameter( "progressid" ).

I commented out the use of the progress bar and found
the request consumption moves to the context creation
@ m_engine.createContext( req, WikiContext.ATTACH );

Once it is consumed there, there is nothing left for the
upload.parseRequest (req ) to read.

I realize that I consumed the request by reading it for the
debug message, but I only used it once per test run to
determine where it was consumed. In the following log
extract, that was at time 2015-11-25 14:05:41.892,
which was after the createContext and before the
upload.parseRequest.

I'm inexperienced with the doFilter mechanism, and I see
that it is part of the exception dump, and I don't know if
that is working or not, but since upload.parseRequest ( req )
is returning an empty fileItems list, I suspect there is
something going on there. But I'm in over my head here.

This is the log extract, starting right after the container JAAS
has authorized the user.

=================

2015-11-25 14:05:41.797 [http-bio-8080-exec-1] DEBUG AttachmentServlet 168 - UploadServlet initialized. Using /home/testwiki/storage//attach-tmp for temporary storage.
2015-11-25 14:05:41.797 [http-bio-8080-exec-1] DEBUG SessionMonitor 117 - Looking up WikiSession for session ID=8974D02E77F76467ACB66B0EAC09C4D7... found it
2015-11-25 14:05:41.797 [http-bio-8080-exec-1] DEBUG WikiSession 851 - Custom com.apache.wiki.WikiSession.isIPV4Address has been entered
2015-11-25 14:05:41.798 [http-bio-8080-exec-1] DEBUG SessionMonitor 117 - Looking up WikiSession for session ID=8974D02E77F76467ACB66B0EAC09C4D7... found it
2015-11-25 14:05:41.798 [http-bio-8080-exec-1] DEBUG SessionMonitor 117 - Looking up WikiSession for session ID=8974D02E77F76467ACB66B0EAC09C4D7... found it
2015-11-25 14:05:41.798 [http-bio-8080-exec-1] DEBUG WikiServletFilter 164 - Executed security filters for user=AdminUser, path=/TestWiki/attach
2015-11-25 14:05:41.799 [http-bio-8080-exec-1] DEBUG AttachmentServlet 437 - AttachmentServlet doPost entered
2015-11-25 14:05:41.799 [http-bio-8080-exec-1] DEBUG AttachmentServlet 490 - AttachmentServlet upload entered
2015-11-25 14:05:41.820 [http-bio-8080-exec-1] DEBUG AttachmentServlet 509 - AttachmentServlet upload; starting try
2015-11-25 14:05:41.887 [http-bio-8080-exec-1] DEBUG SessionMonitor 117 - Looking up WikiSession for session ID=8974D02E77F76467ACB66B0EAC09C4D7... found it
2015-11-25 14:05:41.888 [http-bio-8080-exec-1] DEBUG WikiContext 248 - Creating WikiContext for session ID=8974D02E77F76467ACB66B0EAC09C4D7; target=Main
2015-11-25 14:05:41.892 [http-bio-8080-exec-1] DEBUG AttachmentServlet 515 - AttachmentServlet upload; after wikiContext req=
2015-11-25 14:05:41.903 [http-bio-8080-exec-1] DEBUG AttachmentServlet 535 - AttachmentServlet upload; fileItems.size()=0
2015-11-25 14:05:41.903 [http-bio-8080-exec-1] DEBUG AttachmentServlet 536 - AttachmentServlet upload; before for loop
2015-11-25 14:05:41.903 [http-bio-8080-exec-1] DEBUG AttachmentServlet 579 - AttachmentServlet upload; after for loop
2015-11-25 14:05:41.903 [http-bio-8080-exec-1] DEBUG AttachmentServlet 583 - AttachmentServlet upload; fileItems size was 0; doing redirect to errorPage
2015-11-25 14:05:41.904 [http-bio-8080-exec-1] DEBUG AttachmentServlet 640 - AttachmentServlet upload; after multiple catch, in finally
2015-11-25 14:05:41.904 [http-bio-8080-exec-1] DEBUG SessionMonitor 117 - Looking up WikiSession for session ID=8974D02E77F76467ACB66B0EAC09C4D7... found it
2015-11-25 14:05:41.904 [http-bio-8080-exec-1] DEBUG AttachmentServlet 451 - AttachmentServlet doPost catch doing redirect
2015-11-25 14:05:41.904 [http-bio-8080-exec-1] DEBUG AttachmentServlet 454 - AttachmentServlet doPost exiting
2015-11-25 14:05:41.944 [http-bio-8080-exec-2] DEBUG WikiServletFilter 107 - Using ByteArrayResponseWrapper
2015-11-25 14:05:41.944 [http-bio-8080-exec-2] DEBUG SessionMonitor 117 - Looking up WikiSession for session ID=8974D02E77F76467ACB66B0EAC09C4D7... found it
2015-11-25 14:05:41.945 [http-bio-8080-exec-2] DEBUG WikiSession 851 - Custom com.apache.wiki.WikiSession.isIPV4Address has been entered
2015-11-25 14:05:41.945 [http-bio-8080-exec-2] DEBUG SessionMonitor 117 - Looking up WikiSession for session ID=8974D02E77F76467ACB66B0EAC09C4D7... found it
2015-11-25 14:05:41.945 [http-bio-8080-exec-2] DEBUG SessionMonitor 117 - Looking up WikiSession for session ID=8974D02E77F76467ACB66B0EAC09C4D7... found it
2015-11-25 14:05:41.945 [http-bio-8080-exec-2] DEBUG WikiServletFilter 164 - Executed security filters for user=AdminUser, path=/TestWiki/Error.jsp
2015-11-25 14:05:41.963 [http-bio-8080-exec-2] DEBUG SessionMonitor 117 - Looking up WikiSession for session ID=8974D02E77F76467ACB66B0EAC09C4D7... found it
2015-11-25 14:05:41.965 [http-bio-8080-exec-2] DEBUG WikiContext 248 - Creating WikiContext for session ID=8974D02E77F76467ACB66B0EAC09C4D7; target=Error
2015-11-25 14:05:41.966 [http-bio-8080-exec-2] DEBUG JSPWiki 125 - Error.jsp exception is:
2015-11-25 14:05:41.967 [http-bio-8080-exec-2] ERROR WikiTagBase 84 - WikiTagBase pageContext IS NOT NULL
2015-11-25 14:05:41.970 [http-bio-8080-exec-2] ERROR WikiTagBase 97 - Tag failed
javax.servlet.jsp.JspException: WikiContext may not be NULL - serious internal problem!
at org.apache.wiki.tags.WikiTagBase.doStartTag(WikiTagBase.java:90)
at org.apache.jsp.Error_jsp._jspx_meth_wiki_005fMessages_005f0(Error_jsp.java:193)
at org.apache.jsp.Error_jsp._jspService(Error_jsp.java:138)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.wiki.ui.WikiServletFilter.doFilter(WikiServletFilter.java:177)
at org.apache.wiki.ui.WikiJSPFilter.doFilter(WikiJSPFilter.java:121)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.authenticator.SingleSignOn.invoke(SingleSignOn.java:341)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:724)
2015-11-25 14:05:41.973 [http-bio-8080-exec-2] ERROR WikiTagBase 116 - Tag failed, check logs: WikiContext may not be NULL - serious internal problem!
javax.servlet.jsp.JspException: Tag failed, check logs: WikiContext may not be NULL - serious internal problem!
at org.apache.wiki.tags.WikiTagBase.doStartTag(WikiTagBase.java:98)
at org.apache.jsp.Error_jsp._jspx_meth_wiki_005fMessages_005f0(Error_jsp.java:193)
at org.apache.jsp.Error_jsp._jspService(Error_jsp.java:138)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.wiki.ui.WikiServletFilter.doFilter(WikiServletFilter.java:177)
at org.apache.wiki.ui.WikiJSPFilter.doFilter(WikiJSPFilter.java:121)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.authenticator.SingleSignOn.invoke(SingleSignOn.java:341)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:724)