Would be even better if the result of `get()` was cached in a local variable so it wouldn't have to be called again a couple lines below.
Similarly, the value that is `put()` to the map could be stored in that local variable.

(it really surprises me that `get()` could be faster than `containsKey()`, particularly given the actual implementation of `get()` vs. `containsKey()` in GWT's emulation of `HashMap`/`AbstractMap`)