Fixing javadoc errors and warnings

jetty-server/src/main/java/org/eclipse/jetty/server/handler/GzipHandler.java

@@ -48,7 +48,7 @@ import org.eclipse.jetty.util.log.Log;
  * 
  * <p>
  * Compressing the content can greatly improve the network bandwidth usage, but at a cost of memory and CPU cycles. If this handler is used for static content,
- * then use of efficient direct NIO may be prevented, thus use of the gzip mechanism of the {@link org.eclipse.jetty.servlet.DefaultServlet} is advised instead.
+ * then use of efficient direct NIO may be prevented, thus use of the gzip mechanism of the <code>org.eclipse.jetty.servlet.DefaultServlet</code> is advised instead.
  * </p>
  */
 public class GzipHandler extends HandlerWrapper

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

@@ -81,7 +81,7 @@ public abstract class AbstractSession implements AbstractSessionManager.SessionI
     
     /* ------------------------------------------------------------- */
     /**
-     * @return True is the session is invalid or passivated.
+     * asserts that the session is valid
      */
     protected void checkValid() throws IllegalStateException
     {

jetty-server/src/main/java/org/eclipse/jetty/server/session/JDBCSessionManager.java

@@ -680,7 +680,7 @@ public class JDBCSessionManager extends AbstractSessionManager
     /** 
      * Add a newly created session to our in-memory list for this node and persist it.
      * 
-     * @see org.eclipse.jetty.server.session.AbstractSessionManager#addSession(org.eclipse.jetty.server.session.AbstractSessionManager.AbstractSession)
+     * @see org.eclipse.jetty.server.session.AbstractSessionManager#addSession(org.eclipse.jetty.server.session.AbstractSession)
      */
     @Override
     protected void addSession(AbstractSession session)