Major Description
Currently our MockAccumulo uses a Key,Value Map to emulate the back end. And next() calls just get the Key and Value from the map, with no object reuse. This can cause users to create iterators which use an object that succeed in Mock but fail on the real system. We should have some sort of system to better emulate the appropriate behavior.
I talked to Adam offline about this, and there were a few initial ideas, which basically involve reusing an object and reading in the Value from the Map. However, we think it would be a better idea to create a special Key and Value extension which Mock uses. This special class would have a flag that gets set by the internal Mock next() method to 'invalidate' the old Key and Value, so if there are any indications of reuse, they throw an exception with a description of their misuse.
There still may be an issue with that implementation if users are messing with internal byte arrays, so we may need to make an additional step to either overwrite that data with an informative message and/or have some sort of output when people get the byte array to warn them.
Additionally, Key use may not be an actual issue, since I think only RelativeKeys are reused under the hood. However, this may not be the case for using MapFiles. Keith can probably quickly answer this question.