PIVOT-976: More Javadoc fixes for the warnings from Java 8.

Continuing on down the list, basically.  Almost all of these are
@param descriptions, although some are @return.

Also continued a little bit using the Utils.checkNull method in some
places in the components that were update.  This is a bit off-track
for Javadoc, but there is no separate JIRA for these changes, so ....



git-svn-id: https://svn.apache.org/repos/asf/pivot/trunk@1712454 13f79535-47bb-0310-9956-ffa450edef68
16 files changed