Run a mutation with a external id

Users Dgraph
2

Yes.

In the documentation says:

As of version 0.8 Dgraph doesn’t natively support such external IDs as node identifiers. Instead, external IDs can be stored as properties of a node with an xid edge. For example, from the above, the predicate names are valid in Dgraph, but the node identified with <http://schema.org/Person> could be identified in Dgraph with a UID, say 0x123 , and an edge

Dgraph will never identify <lianlian> as BlankNode or something valid.
As you can see at Get started with Dgraph
In the RDF format used by Dgraph the Entity will always represent a standard Dgraph entity identification. Be it a BlankNode or a UID (eg: 0x1a35).

This part of the Get started with Dgraph documentation is teaching how to use this xid as part of the Node itself. Not as a RDF markup identifier.

In other words, it is transforming this
_: userA <http://schema.org/type> <http://schema.org/Person>.
into a node with UID ==> “0x123” or
<0x123> <xid> "http://schema.org/Person".

It transforms the <http://schema.org/Person> into a Dgraph Node
<0x123> <xid> "http://schema.org/Person".