bean: unchecked call to getMethod() as a member of the raw type Class

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

Change-Id: Ib548b47c412394e1518fea42b83d05a36c1655c8
Reviewed-on: https://gerrit.libreoffice.org/11477
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>