We should realize JAX-RS 1.1 is implemented as Java Servlet and its configuration + JAX-RS application wiring is made above Java Servlet 3.0 Specification in EAP6/AS7.

Our JAX-RS implementation - RESTEasy - must follow every possibility specified by previous mentioned standards.

From Java Servlet specification version 2.5 is possible to have multiple URL in one servlet mapping like (way 1):

<servlet-mapping>
        <servlet-name>MappedServlet</servlet-name>
        <url-pattern>/mapping1/*</url-pattern>
        <url-pattern>/mapping2/*</url-pattern>
</servlet-mapping>

for details see SRV.19.0.3 Multiple Occurrences of Servlet Mappings inside Java Servlet standard.

It is also possible to have multiple servlet mapping specification to one servlet like (way 2):

<servlet-mapping>
        <servlet-name>MappedServlet</servlet-name>
        <url-pattern>/mapping1/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
        <servlet-name>MappedServlet</servlet-name>
        <url-pattern>/mapping2/*</url-pattern>
</servlet-mapping>

This option has come from first Java Servlet specification.

In RESTEasy no one above way works! It seems like only first mapping occurence is recognized (either way 1 or way 2) and every other is silently ignored -> a such resources are unavailable and HTTP Code 404 is occurred when somebody tries access them.

This is very bad approach - it is unable to do (only) some part of JAX-RS application/resources available only after proper authentication - this is only the first example/scenario I can imagine, I'm sure there are existing others useful cases for to do it in this way too.