Activity definition support

All data are SerDe into json object internally for regular java objects.

In case I would like to change my activity return type to void or any other. Any issues I can expect?

My guess Temporal should skip previously returned value and continue workflow as this value are not used workflow.

It is expected that multiple activity versions will be active during deployments. So it could lead to failures if return types are not compatible. We recommend returning a structure as an activity result and changing this structure fields in a backward compatible manner.