This uses an extensibility mechanism similar to that of WhoisCommandFactory
and CustomLogicFactory, namely, that a fully qualified Java class is
specified in the YAML file for each environment with the allocation token
custom logic to be used. By default, this points to a no-op base class
that does nothing. Users that wish to add their own allocation token
custom logic can simply create a new class that extends
AllocationTokenCustomLogic and then configure it in their .yaml config
files.
This also renames the existing *FlowCustomLogic *Flow instance variables
from customLogic to flowCustomLogic, to avoid the potential confusion with
the new AllocationTokenCustomLogic class that also now exists.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=183003112
