Weird behaviour of deserializeMap

[libre-man]

The smithy generator overrides the deserializeMap function, however I think the behaviour is somewhat counter intuitive.

First of all for sparse maps it will ignore null values, but not undefined values. I would expect that if null values are ignored, that undefined values are definitely ignored. This is especially confusing as JSON.stringify does ignore undefined values, but not null values.

Furthermore, a new object is constructed for every key. While this makes the reduce a nice pure function, it does mean it is way slower than it needs to be, allocating a new object for each key it adds.