[midPoint] Mandatory fields

[Pavol Mederly]

Hello Petr,

> Anyway, since this is our first PoC, we have some customer feedback:
> - is it possible to override system messages (like "output definition 
> must be specified for asIs expression evaluator in objectTemplate") 
> with something less technical? Technical detail can stay in error stack..

thank you for the feedback!

Yes we know that the system messages definitely should be improved (see 
e.g. https://jira.evolveum.com/browse/MID-1092).

However, midPoint configuration is inherently quite complex thing. So 
any messages related to it (like the one you provided as an example) are 
complex as well. But maybe as you suggested, the main reason could be 
described more understandably, e.g. "midPoint configuration problem", 
with the details in the subsequent lines or in stack trace, as you wrote.

Best regards,
Pavol