[Attempto] Thread safe about Ontology class

[Changyuan Yu]

Hi,
  In order to make AceWiki RESTful api servlet be synchronized with
original AceWiki, I share the same Ontology object between two
servlet(by save the object in ServletContext).  Currently, I do not
encounter any problem, but race condition will not easily happen
without heavy test or special designed test.
  I read the code, and find many methods in Ontology are marked as
'synchronized', but there is no document explicit say that the class
is thread-safe. So I want ask is Ontology class thread safe? And how
about other classes?

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Best regards,
Changyuan