In the init-Method of /varia/src/main/org/jboss/invocation/http/servlet/NamingFactoryServlet.java
an <init-param> "accessorOpName" ist fetchted:
proxyAttribute = config.getInitParameter("accessorOpName");
In the corresponding /varia/src/resources/services/invoker/http/web.xml there isn't this <init-param>
but instead there is:
<init-param>
<param-name>proxyAttribute</param-name>
<param-value>Proxy</param-value>
</init-param>

Therefore in the init-Method of /varia/src/main/org/jboss/invocation/http/servlet/NamingFactoryServlet.java
proxyAttribute is always null and proxyAttribute is set to the default value:
if( proxyAttribute == null )
proxyAttribute = "Proxy";

patch:
Change either: proxyAttribute = config.getInitParameter("accessorOpName");
to proxyAttribute = config.getInitParameter("proxyAttribute");
or <param-name>proxyAttribute</param-name>
to <param-name>accessorOpName</param-name>