galgonek opened a new issue, #2994:
URL: https://github.com/apache/jena/issues/2994

   ### Version
   
   5.3.0
   
   ### What happened?
   
   During my experiments, I observed that Jena incorrectly evaluates the 
following federated query, which uses a blank node:
   
   ```sparql
   PREFIX sd: <http://www.w3.org/ns/sparql-service-description#>
   
   SELECT * WHERE {
     BIND(bnode() as ?BN)
   
     SERVICE <https://idsm.elixir-czech.cz/sparql/endpoint/idsm> {
         ?S sd:endpoint ?BN.
     }
   }
   ```
   
   This query should not return any solutions because blank nodes are only 
locally scoped within RDF stores. However, it returns the following result:
   
   
   
   | ?BN | ?S |
   |-|-|
   | _:b0 | &lt;https://idsm.elixir-czech.cz/sparql/endpoint/idsm&gt; |
   
   The problem arises because Jena inappropriately substitutes `?BN` with 
`_:b0` when it evaluates the service pattern:
   
   ```sparql
   SELECT  *
   WHERE
     { ?S  <http://www.w3.org/ns/sparql-service-description#endpoint>  _:b0 }
   ```
   
   ### Relevant output and stacktrace
   
   ```shell
   
   ```
   
   ### Are you interested in making a pull request?
   
   None


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