Fix StateMachineVersion callback context spotbug issue

[hongkuntian]

Issue #, if available:
N/A

Description of changes:
Fix spotBug issue identified in CallbackContext class for StateMachineVersion resource

EQ_OVERRIDING_EQUALS_NOT_SYMMETRIC: equals method overrides equals in superclass and may not be symmetric

This class defines an equals method that overrides an equals method in a superclass. Both equals methods methods use instanceof in the determination of whether two objects are equal. This is fraught with peril, since it is important that the equals method is symmetrical (in other words, a.equals(b) == b.equals(a)). If B is a subtype of A, and A's equals method checks that the argument is an instanceof A, and B's equals method checks that the argument is an instanceof B, it is quite likely that the equivalence relation defined by these methods is not symmetric.

Culprit is that the super class implements both equals and hashCode

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