Does GlassFish servlet container use that catalina?

I am running the same servlet application in both Apache Tomcat and GlassFish servers. I wanted to see the ServletConfig and ServletContext implementation class names. Surprisingly, I found that GlassFish is also using from Apache Tomcat’s catalina classes. Is my observation correct? If yes, why isn’t GlassFish using its own servlet implementation classes?

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Answer

According to this FAQ entry the Glassfish web container is a fork of Tomcat 5.5. Therefore it uses the same package names, although Tomcat’s code has evolved a lot since the fork.