Decouple meta-model with the settings object.
Simplifies the mapping loader construction.
Rewrite the mapping factory construction.
Remove setter and getter methods to collect constraint from Clause
interface. The constraint handling is replaced by setter and getter
filters from  Query interface.
Creating class or property mapping objects require the subject-map value
or subject-map and object-map values.
Refactor the mapping object to include a unique signature.
Create the class- and property-mapping using the constructor instead of
using the factory.
The complete mapping object is created using the factory method.
The complete mapping object is created using the factory method.
Throw an exception when the property URI is null.
Throw an exception when the property URI is null.
Minor change on the exception message.