only send metatadata if not null
only send metatadata if not null

Impactstory/sherlockoa,Impactstory/sherlockoa,Impactstory/oadoi,Impactstory/citeas-api,Impactstory/oadoi,Impactstory/oadoi,Impactstory/citeas-api,Impactstory/citeas-api