Xlint warnings for Java

[Rik]

Can someone who is familiar with Java take a look at bug
https://savannah.gnu.org/bugs/index.php?53550.

This is about warning messages emitted by Xlint.  I think they may be
relatively easy to fix, but I don't know the language well enough.  For
example, here is one of the warnings:

Octave.java:154: warning: [unchecked] unchecked call to add(E) as a member
of the raw type LinkedList
          invokeList.add (r);
                         ^
I just uploaded a log file with the unchecked warnings and I will do
another one for the deprecations warnings.

--Rik