D4.1 OpenAIRE Data model extension

Summary
The D4.1 OpenAIRE Data model extension (M2-ongoing, R-wiki) deliverable includes the extension to the OpenAIRE data model (https://issue.openaire.research-infrastructures.eu/projects/openaire2020-wiki/wiki/D81_OpenAIRE_Data_Model_Specification) required to model research methods and packages of research artefacts.