I need to write another DOIConnector to support some security constraints of our computing center. While doing so I noticed that the DOIIdentifierProvider does things only the DOIConnector should do. This change helps to keep the separation between both parts clean.
In detail: when the DOIIdentifierProvider has to register a DOI at the registration agency, it checks whether the DOI is reserved and perform a reservation if it is not. The behavior is founded in a rule of DataCite that wants us to reserve a DOI before it is registered. As other registration agency may have other rules this should be checked by the DataCiteConnector and not by the DOIIdentifierProvider. The DataCiteConnector encapsulates all DataCite specific part while the DOIIdentifierProvider should handle everything on the side of DSpace.
The second Bugfix is just a typo. A static final field in the DOIIdentifierException should be renamed.
Both bugfixes should goes into DSpace 4.0 so that they get public before anyone else begins to implement another DOIConnector.