Getting error JBWEB000043: Cannot create a session after the response has been committed

Issue

The below message is logged in server.log. What does mean the log?

18:25:40,192 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[default-host].[/echo].[org.example.servlet.InvalidateServlet]] (http-/127.0.0.1:8080-1) JBWEB000236: Servlet.service() for servlet org.example.servlet.InvalidateServlet threw exception: java.lang.IllegalStateException: JBWEB000043: Cannot create a session after the response has been committed
    at org.apache.catalina.connector.Request.doGetSession(Request.java:2647) [jbossweb-7.4.10.Final-redhat-1.jar:7.4.10.Final-redhat-1]
    at org.apache.catalina.connector.Request.getSession(Request.java:2381) [jbossweb-7.4.10.Final-redhat-1.jar:7.4.10.Final-redhat-1]
    at org.apache.catalina.connector.RequestFacade.getSession(RequestFacade.java:791) [jbossweb-7.4.10.Final-redhat-1.jar:7.4.10.Final-redhat-1]
    at org.apache.catalina.connector.RequestFacade.getSession(RequestFacade.java:801) [jbossweb-7.4.10.Final-redhat-1.jar:7.4.10.Final-redhat-1]
    at com.redhat.cee.example.ExampleServlet.doGet(InvalidateServlet.java:23) [classes:]