Fix hookTokens to be clearable outside the class

[eileenmcnaughton]

Overview

Fix hookTokens to be clearable outside the class

Before

Tests can't unset the proerty in the class easily

After

hook tokens can be flushed from within unit tests

Technical Details

Comments

[civibot]

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[totten]

Lots of test coverage in this area. Looks like a safe refactoring.