Service Enhancer breaks literals in service clause

[Aklakan]

This issue actually needs to be fixed at the service enhancer jena plugin - but for now I document it here:

The following example incorrectly uses <env:S> (string substitution) rather than env://S (IRI substitution).

S=https://query.wikidata.org/sparql rpt integrate 'SELECT * { SERVICE <env:S> { <http://www.wikidata.org/entity/Q54837> ?p ?o } }'

This causes a NPE in my service enhancer plugin. The plugin should not interfere and just pass on the execution request to the engine.

Caused by: java.lang.NullPointerException: Cannot invoke "java.util.List.size()" because "opts" is null
	at org.apache.jena.sparql.service.enhancer.impl.ChainingServiceExecutorBulkServiceEnhancer.createExecution(ChainingServiceExecutorBulkServiceEnhancer.java:53) ~[jena-serviceenhancer-4.8.0-SNAPSHOT.jar:4.8.0-SNAPSHOT]