unchecked call to getDeclaredMethod(String,Class<?>...)

http://docs.oracle.com/javase/tutorial/reflect/class/classTrouble.html

Change-Id: I293e7ad3ace1a8876c34d7ffd070b49807a8b0a6
Reviewed-on: https://gerrit.libreoffice.org/11882
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>