XPath queries: compatibility for missing @ in front of property names

XPath queries with conditions of the form

[id='test']

are not problematic. Jackrabbit 2.x interpreted such conditions as

[@id='test']

, and Oak currently interprets them as

[@id/* = 'test']

, as this is the expected behavior for conditions of the form

[jcr:contains(id, 'test')]

.

I believe the condition

[id='test']

is illegal, and it would be better to throw an exception instead, saying a @ is missing.