Exported prior reviews from Gerrit Code Review
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* Added @Type annotation to explicitly specify return type for getters.
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* Fixed implementation of mapped fields and methods of behaviour classes.
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* Fixed comments.
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* Renamed annotations and introduced Filterable interface for property sets.
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* Clean up and remove @iri annotation.
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* Extend the property set factory interface.
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* Use Guice to inject property sets.
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* Implement PropertySetOwner interface.
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* Add accessor for underlying property set of UnmodifiablePropertySet.
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* added license information
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* updated license information
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* Fixed: sometimes the returned set was not unmodifiable