[homekit] some cleanups

[yfre]

some cleanup and alignment of accessories implementations.
key changes

• make consistent use of BooleanItemReader and some other helpers
• annotate with @NonNullByDefault where possible
• make final where possible
• use import static
• improve logging at few places

Signed-off-by: Eugen Freiter [email protected]

[Hilbrand]

Thanks for the clean up. Just a general comment. Where possible can inline the null annotations on fields and variables: private @Nullable String something;.

[yfre]

@cpmeister @Hilbrand
what is your view on "final" for parameters? is there a guidance for openHAB?
e.g.
private static CurrentFanStateCharacteristic createCurrentFanStateCharacteristic(final HomekitTaggedItem taggedItem, HomekitAccessoryUpdater updater) {

should we make both "final" or remove "final" ? both parameters will not get new objects assigned in the method.
personally, i dont see much advantage of having "final" for parameters but it does not hurt either.

just want to make it consistent.

[yfre]

i have checked the usage of final in parameters in openHAB core and some mature extensions like hueemulation and it looks like in majority of cases final is not used for parameters.
so, i have removed final from parameters in homekit binding

[Hilbrand]

@yfre Seems fine. (I had this comment prepared, but somehow forgot to click comment): There is no definite preference on final parameters. I think most people do prefer not to make them final as it would make code more verbose and harder to read is the thought. I personally prefer to make them final. And for some reason some version of the Eclipse setup of openHAB will make all parameters final when you save a file, although I'm not sure if that is intentional or a bug somewhere that causes this setting to be enabled.