Prior to this commit, `SimpleKey` would be used in Spring Framework's
caching support and its `hashCode` value would be used to efficiently
store this key in data structures.
While the current hashcode strategy works, the resulting values don't
spread well enough when input keys are sequential (which is often the
case). This can have negative performance impacts, depending on the
data structures used by the cache implementation.
This commit improves the `hashCode` function with a mixer to better
spread the hash values. This is using the mixer function from the
MurMur3 hash algorithm.
Closes gh-34483
466ac6b703