[HBASE-18931] Make ObserverContext an interface and remove private/testing methods

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.0.0-alpha-4, 2.0.0
• Component/s: Coprocessors
• Labels: incompatible
• Release Note: Changes ObserverContext from a class to an interface and hides away constructor, testing functions and other internal-only functions in the implementation class.
• Assignee: Apekshit Sharma
• Reporter: Apekshit Sharma
• Created: 04/Oct/17 00:07
• Updated: 21/Mar/18 22:16
• Resolved: 06/Oct/17 07:02

Description

ObserverContext is IA.LimitedPrivate because CP implementations want getEnvironment(), bypass(), etc.
We can split interface and implementations (suggested by [~Apache9]).