  We present a solution to the Round-Trip Migration case of the Transformation
Tool Contest 2020, based on the Henshin model transformation language. The task
is to support four scenarios of transformations between two versions of the
same data metamodel, a problem inspired by the application scenario of Web API
migration, where such a round-trip migration methodology might mitigate
drawbacks of the conventional "instant" migration style. Our solution relies on
Henshin's visual syntax, which seems well-suited to capture the problem on an
intuitive level, since the syntax is already similar to the scenario
illustrations in the case description. We discuss the five evaluation criteria
expressiveness, comprehensibility, bidirectionality, performance, and
reusability.
