"Israel is claiming the documents as part of its cultural heritage arguing that because Kafka was Jewish, his works belong there."
Ever heard so much garbage in your life? Like, say, just because some random author was Christian or whatever, his work should belong to his church, which he may not even have been particularly into or interested in.
I'm bothered by the whole notion that the work of any writer or artist is "owned" by any group, whether that group is defined racially, nationally, religiously, sexually, etc. You don't have to be Jewish to appreciate Kafka any more than you have to be Russian to appreciate Dostoevsky. Come to think of it, the attitude reminds me of the post I made about the shrill film critic who told David Cronenberg that only a homosexual can appreciate Burroughs' work.
Having said that, Israel's claim on Kafka doesn't bother me as much as the hypocrisy of their claim on Baruch Spinoza, who rejected Judaism and was rejected by (and literally cursed by) the Jewish community of his times. Yet Israel has the audacity to put the philosopher on their currency.