ENA secondary accession field not imported

Fetching ENA record M12975 results in ENA AH002001. However, since M12975 is not added to the returned sequence, cross-reference round-tripping is impossible.

Enabling Castor debug shows these responses:

#startElement: secondaryAccession
unable to find FieldDescriptor for 'secondaryAccession' in ClassDescriptor of embl-entry - ignoring extra element.
#characters: M12975-M12977
#endElement: secondaryAccession
#characters:

secondaryAccession field doesn't seem to be in the mapping file, and further more, contractions are used in this example (found quite by chance) - which will need to be interpolated in order to support accession matching.