Fix registration update processing

Only update registration properties for which a non-null value has beenprovided
I agree if we used commons only for that it would be overkill but we use commons for: IOUtils, ArrayUtils, StringUtils so we use it for Validate parameters. So well let's depend on it.

A null value passed to a method is like a out-of-range should generate a IllegalArgumentException because it's violating the method contract.
So if I see a IAEx => I violated a contract, if I see a NPEx => my code is not defensive enough.
IMO It 's how Apache commons Validate was designed.