Why is com.sun.config.ConfigureListener the frist one to be executed when T

Question

In JSF1.1 guessNumber demo
The web.xml does not define a ServletContextListener.
why is com.sun.config.ConfigureListener the frist one to be executed when Tomcat begins running?
web.xml:
<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<display-name>JavaServer Faces Guess Number Sample Application</display-name>
<description>
JavaServer Faces Guess Number Sample Application
</description>
<context-param>
<param-name>javax.faces.STATE_SAVING_METHOD</param-name>
<param-value>client</param-value>
</context-param>
<context-param>
<param-name>com.sun.faces.validateXml</param-name>
<param-value>true</param-value>
<description>
Set this flag to true if you want the JavaServer Faces
Reference Implementation to validate the XML in your
faces-config.xml resources against the DTD. Default
value is false.
</description>
</context-param>
<context-param>
<param-name>com.sun.faces.verifyObjects</param-name>
<param-value>true</param-value>
<description>
Set this flag to true if you want the JavaServer Faces
Reference Implementation to verify that all of the application
objects you have configured (components, converters,
renderers, and validators) can be successfully created.
Default value is false.
</description>
</context-param>
<!-- Faces Servlet -->
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup> 1 </load-on-startup>
</servlet>
<!-- Faces Servlet Mapping -->
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>/guess/*</url-pattern>
</servlet-mapping>
<security-constraint>
<!-- This security constraint illustrates how JSP pages
with JavaServer Faces components can be protected from
being accessed without going through the Faces Servlet.
The security constraint ensures that the Faces Servlet will
be used or the pages will not be processed. -->
<display-name>Restrict access to JSP pages</display-name>
<web-resource-collection>
<web-resource-name>
Restrict access to JSP pages
</web-resource-name>
<url-pattern>/greeting.jsp</url-pattern>
<url-pattern>/response.jsp</url-pattern>
</web-resource-collection>
<auth-constraint>
<description>
With no roles defined, no access granted
</description>
</auth-constraint>
</security-constraint>
</web-app>
com.sun.config.ConfigureListener is the frist one to be executed when Tomcat begins running?
why?
Thread: main
<init>() : 98, com.sun.faces.application.ApplicationAssociate, ApplicationAssociate.java
<init>() : 98, com.sun.faces.application.ApplicationImpl, ApplicationImpl.java
getApplication() : 74, com.sun.faces.application.ApplicationFactoryImpl, ApplicationFactoryImpl.java
application() : 384, com.sun.faces.config.ConfigureListener, ConfigureListener.java
configure() : 427, com.sun.faces.config.ConfigureListener, ConfigureListener.java
configure() : 402, com.sun.faces.config.ConfigureListener, ConfigureListener.java
contextInitialized() : 332, com.sun.faces.config.ConfigureListener, ConfigureListener.java
listenerStart() : 3669, org.apache.catalina.core.StandardContext, StandardContext.java
start() : 4104, org.apache.catalina.core.StandardContext, StandardContext.java
start() : 1012, org.apache.catalina.core.ContainerBase, ContainerBase.java
start() : 718, org.apache.catalina.core.StandardHost, StandardHost.java
start() : 1012, org.apache.catalina.core.ContainerBase, ContainerBase.java
start() : 442, org.apache.catalina.core.StandardEngine, StandardEngine.java
start() : 450, org.apache.catalina.core.StandardService, StandardService.java
start() : 683, org.apache.catalina.core.StandardServer, StandardServer.java
start() : 537, org.apache.catalina.startup.Catalina, Catalina.java
invoke0() : -1, sun.reflect.NativeMethodAccessorImpl, NativeMethodAccessorImpl.java
invoke() : 39, sun.reflect.NativeMethodAccessorImpl, NativeMethodAccessorImpl.java
invoke() : 25, sun.reflect.DelegatingMethodAccessorImpl, DelegatingMethodAccessorImpl.java
invoke() : 585, java.lang.reflect.Method, Method.java
start() : 271, org.apache.catalina.startup.Bootstrap, Bootstrap.java
main() : 409, org.apache.catalina.startup.Bootstrap, Bootstrap.java

Answer 1

why is com.sun.config.ConfigureListener the frist one to be executed when Tomcat begins running(no config in web.xml)?