436345 Refactor AbstractSession to minimize burden on subclasses to implement behaviour

Conflicts:
	jetty-server/src/main/java/org/eclipse/jetty/server/session/AbstractSession.java
	jetty-server/src/main/java/org/eclipse/jetty/server/session/MemSession.java

tests/test-sessions/test-infinispan-sessions/pom.xml

@@ -21,11 +21,14 @@
   <parent>
     <groupId>org.eclipse.jetty.tests</groupId>
     <artifactId>test-sessions-parent</artifactId>
-    <version>9.1.6-SNAPSHOT</version>
+    <version>9.3.0-SNAPSHOT</version>
   </parent>
   <artifactId>test-infinispan-sessions</artifactId>
   <name>Jetty Tests :: Sessions :: Infinispan</name>
   <url>http://www.eclipse.org/jetty</url>
+  <properties>
+    <bundle-symbolic-name>${project.groupId}.sessions.infinispan</bundle-symbolic-name>
+  </properties>
   <build>
     <plugins>
       <plugin>