In OpenAIRE/oai_datacite export, include "Custom terms specific to this dataset" and link to custom licenses in `rights` property

Overview of the Feature Request

When the user adds custom dataset terms to their dataset, the OpenAIRE/oai_datacite export should include a rights property with "Custom terms specific to this dataset" and in the rightsUri property include the link to custom license, as the DataCite/Datacite export does.

Currently, the OpenAIRE/oai_datacite export does not include anything about users' custom dataset terms.

This issue is part of a larger effort to align both metadata exports, described in https://github.com/IQSS/dataverse/issues/11916 and https://github.com/IQSS/dataverse/issues/12281.

What kind of user is the feature intended for?

API User, Superuser, and Sysadmin

What inspired the request?

This is part of a larger effort to align the OpenAIRE/oai_datacite and DataCite/Datacite metadata exports. There is more context at https://github.com/IQSS/dataverse/issues/11916 and https://github.com/IQSS/dataverse/issues/12281.

What existing behavior do you want changed?

Currently, when the user chooses "Custom Dataset Terms" from the "License/Data Use Agreement" and enters information in the fields that appear in the Dataset Terms panel...

... the OpenAIRE/oai_datacite export does not include anything about the custom dataset terms.

The DataCite/Datacite export includes a rights property with "Custom terms specific to this dataset" and a link to the license in the rightsURI property.

The OpenAIRE/oai_datacite export should be changed to do what the DataCite/Datacite export does.

For example:

<rightsList>
  <rights 
    rightsURI="https://demo.dataverse.org/api/datasets/:persistentId/versions/1.1/customlicense?persistentId=doi:10.70122/FK2/ZBY9AL">Custom terms specific to this dataset</rights>
</rightsList>

Any open or closed issues related to this feature request?

• https://github.com/IQSS/dataverse/issues/11916
• https://github.com/IQSS/dataverse/issues/12281

Start by comparing the OpenAIRE/oai_datacite exporter with the DataCite/Datacite exporter, which already includes custom dataset terms and the custom license link. Trace how the custom license URL is represented, then update the OpenAIRE output so rights contains "Custom terms specific to this dataset" and rightsURI contains that link; verify the generated XML against the example.