Document that createStep/updateStep operations must not run concurrently
This is mostly a documentation issue: when e.g. creating a workflow with 2 steps, the requests for creating the steps must be dispatched sequentially (i.e. await server response before dispatching the next createStep request).
Otherwise, you'll get: error: 'could not execute statement; SQL [n/a]; constraint [item_prev_version_item_id_uq]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement'