FindBugs - avoid NPEs

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1434735 13f79535-47bb-0310-9956-ffa450edef68
FindBugs false positive. It may not be immediately clear why this is a false positive so add a comment to explain it.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1434740 13f79535-47bb-0310-9956-ffa450edef68
Silence a valid FindBugs warning about a problem we have chosen to accept

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1434746 13f79535-47bb-0310-9956-ffa450edef68
Fix FindBugs warning: Incorrect lazy initialization of static field

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1434749 13f79535-47bb-0310-9956-ffa450edef68
Make sure changes to result are visible to all threads currently calling get()

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1434757 13f79535-47bb-0310-9956-ffa450edef68
One final FindBugs false positive

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1434758 13f79535-47bb-0310-9956-ffa450edef68
FindBugs warnings all resolved :)

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1434759 13f79535-47bb-0310-9956-ffa450edef68