Thanks @darius. I would only need:
POST .../session/locale to set the session locale
Context: The idea behind is we would like the OpenMRS metadata to be translated in the session locale and being sent back localized to clients. Currently, metadata are not i18ned, they display in only one language (Bahmni Apps locale not syncing OpenMRS locale (and vice versa)? - #7 by mksd), so as a temporary solution, we are thinking of replacing the metadata values by an i18n message, and wrap all ‘get’ services to return translated metadata strings. For this we need OpenMRS to be aware of the locale selected by the web client.
We think this through a bit more and then yes, we can develop and add it to webservices.rest