There's a 1/32 chance on instances duplicating work

Since the instanceId is recommended to *not* be set, the algorithm generates a random 32 bit instanceId.  This is left shifted 27 positions, which leaves 5 bits of randomness.  On any given invocation, there's a 1/(2^5) chance of colliding with any other invocation.  

For production use cases, it should be recommend that unique instanceIds are provided. 