Standardize CollectionUtils to that of apache.commons
Don't deliver propertyDefinition when not requested
Implement appendContentStream
Output correct latest change event even if there are many "latest"
change events

There should be one event which has the latest flag. This is preventive
coding.
Prevent duplicate property definition when create/update type definition
Implement propertyId uniqueness when propertyDefinition is created
Fix bugs of choices

-output choices via CMIS
-implement constraint exception when values other than choices come in