I think there is something wrong here.

1. emptycollection schema defined schema:size constrained as xsd:integer
2. the context on neurosciencegraph links to the context on schemaorg which defines size as follows

    "size": {
      "@type": "@id",
      "@id": "schema:size"
    }

I think size won't have an @id value...

You should be seeing an error when executing this test. However the workbench doesn't signal it properly.

The error happens before the validator kicks in, when trying to convert the triples into a Jena Model: Exception: Illegal character in path at index 1: A non numeric size. This is Just Jena saying that a field expected to have a @type of @id cannot have this character (space).