Nanopub get published but are not available in the SPARQL endpoint

[vemonet]

Some nanopubs are successfully published but cannot be queried through the SPARQL endpoint

Here are 2 nanopubs published but that can't be found in the SPARQL endpoint https://virtuoso.nps.petapico.org/sparql

• http://purl.org/np/RAFi4vsVj-Xuh6tay2rt29ztwJ-7rDPDCLMIeDqJDMw-A
• http://purl.org/np/RA36RQQ9gJnvC4-m2jEOop5g3X9bAp0jMXRfD_QM3EeLE

Tried with this query:

SELECT * WHERE {
 GRAPH ?g {
  <http://purl.org/np/RAFi4vsVj-Xuh6tay2rt29ztwJ-7rDPDCLMIeDqJDMw-A> ?p ?o .
 }
} LIMIT 10

It is due to the use of the integer data type for dct:created in the pubinfo, it should be xsd:dateTime

dct:created "2022-06-24T09:36:41+00:00"^^xsd:integer

cf. related issue peta-pico/nanopub-services#2

Ideally nanopub-java should fail and show an error message when someone tries to publish a nanopub that does not meet all the requirements to be available through the SPARQL endpoint, otherwise we might end up with a hidden network of semi-valid nanopubs

[tkuhn]

Related to: tkuhn/nanopub-server#14