Sync type parameters can be required

[mitar]

@toomim In this change you wrote that parameters are optional. That is not necessary true. You can define both required and optional parameters (in registration form you define both sets).

[toomim]

My reading of that paragraph is about the definition of a Sync Type, not the use of a Sync Type. It is optional for a Sync Type to specify parameters. If it chooses to do so, it can certainly require one of those parameters to be specified when it is used on a resource.

In any case, I'm open to whatever language makes this clearer.

[mitar]

Yes, at the end I decided to remove mention of parameters in that paragraph, because I could not find a language which would differentiate between two meanings of optional there. If you think parameters should be defined there, maybe we can use "can have parameters" language. Can makes it optional.