Use protected methods vs private

Use protected methods vs private

Application and common code in xacml-pdp is meant to be
available for developers to re-use and/or extend as desired.

Private methods are unnecessary at this time, but could be
re-visited in a later release.

For Honolulu, simply moving to protected to keep functionality
the same. Possibly for Istanbul we can make more changes to
support mixing of ONAP application with custom applications
during runtime.

Issue-ID: POLICY-3305
Change-Id: I6db23bda3c81fdbbf86e39cc2cd2e706d8bee63d
Signed-off-by: Pamela Dragosh <pdragosh@research.att.com>