How to update Contact without removing already stored data?

I'm trying to do a sync adapter to sync my contacts with an webstorage. When I ask this server for any contactupdates on the server-side I get a list of all the new informations added/changed. To update them I'm using the preferred method described here

My problem is that when I make a ContactOperations.newUpdate() and feed it with all the new/changed informations I got from the webserver and then apply it to the ContactsContract.AUTHORITY all the informations already stored on the phone are erased?!?

I make an example to make thinks clear:

I have an contact saved on my phone named: John 'Dady' Doe. Now the SyncAdapter ist invoked by the system, he ask the server for any contactchanges and the server says, that the familyname of this contact now is "Jones". With that information I construct a new ContactProviderOperation.newUpdate() and feed it via .withValue() and apply it. But what Android really does is: It flushes all othere columns and now my contact is named "Jones" (givenName and middleNam开发者_开发知识库e missing -.-).

Is there any way to prevent Android from doing so? Can I pass any parameter like the CALLER_IS_SYNCADAPTER? Or do I need to make my own workaround (hopefully not), like reading the data record first, apply the updates and then apply it to the ContactsContract.AUTHORITY?

Any hint is really appreciated!

/edit: I did further studies by looking at the SyncAdapterExample, especially at the "update a contact"-part, but what I saw kinda shocked me: Google actually does read the contact first, then apply the updates from the server and reapply it to the ContactsContract.AUTHORITY. But they only handle first- and lastname, one email and two phones (normal and mobile). In my case I wan't to handle ALL contactinformations, so it's not feasible to do such a workaround, except there is no other way, which I hope not. Hopefully someone can head me in the right direction for this.

Totally my fault :/

Android is doing everything right, I just failed as hard as this guy ...