it was breaking in com.salesforce.phoenix.end2end.ArithmeticQueryTest#testDecimalUpsertSelect, but passing for the rest of the tests in that class.

The immutableBytePtr should have its buffer only set once and then not again - otherwise its hash code will not be correct. I need the value of the underlying byte[] to stay the same here as I use that row key multiple times when building the KVs in the generated mutation.