D-Net

added serialization, tests

instantiate one SAXReader for each call

fixed format-layout-interpretation concatenation,
doesn't fail when the fieldExtractor returns a null result

added json serialization, builds the matching key one time only

do not upsert sets here in the mapper: we shall delegate to a separate workflow to be run after the OAI feeding is completed.

Always new records to test how faster we go

Always new records to test how faster we go

Refactored class that extracts fields from records. When we can't find an expected index from the configuration to check its repeatability, the field is indexed as repeatable and a counter is updated.

idScheme and idNamespace defined as part of the OAI configuration profile

Removed dependency to dnet-oai-utils to avoid inheritance of unwanted jars such as cnr-rmi-api, cnr-service-common, spring, etc., which should not appear when running a job on the cluster. Needed classes have been copied and adapted so they do not use spring anymore.