core: use private access modifier and rename method.

1. Use private access modifier instead of a public one.
2. Change the method name to indicate it returns list instead of
boolean.

Change-Id: I8fb4aff4a6ad6f4f83f21b148d2f1df3ce6efaf2
Signed-off-by: Maor Lipchuk <mlipchuk@redhat.com>