Fields can have some filter to process the data, for example, HTMLCheckField would return true rather than raw string '1', we should also test this.
Note that the param indicating 'checked' state is matching the state on client-side, the value would be inverted by HTMLCheckField...
Change-Id: Ia9a7a8c46b0a55ecf2d5378a0d0b6cc00cdb54eb
Follow-up changes will use cond-state params in other functions, split this out to make sure it's validated.
Change-Id: Icf358794b11a8f986fbd02c8f1b15ea9d1ef4d15