RFR [13] JDK-8218889: Improperly use of the Optional API

[Xuelei Fan]

Hi,

Could I have the following update reviewed:
     http://cr.openjdk.java.net/~xuelei/8218889/webrev.00/

In general Optional is a good option.  However, 
Optional.ofNullable​(null).get() throws NoSuchElementException, as limit 
the benefits to use Optional.ofNullable​() for null object in the 
session management context.   With this update, the Optional is replaced 
with other coding conventions.

Code cleanup, no new regression test.

Thanks,
Xuelei