I suspect that Hibernate is ignoring insertable = false, updatable = false.

I only see one test that uses @MapKeyColumn(name = "...", insertable = false, updatable = false) (in org.hibernate.test.namingstrategy). That test is only used for testing a custom NamingStrategy. The test doesn't actually do any operations on the mapped entities. I see some problems with that mapping (e.g., there is no existing property that specifies the column, LANGUAGE_CODE, which is marked insertable = false, updatable = false). As a result, when this is fixed, I expect FullyQualifiedEntityNameNamingStrategyTest to fail.

Test case is at http://hwellmann.blogspot.com/2010/07/jpa-20-mapping-map.html .