@Override
    public SubscriptionSession openSubscription(SubscriptionParameters parameters) {
        throw new UnsupportedOperationException("Not supported yet");
    }
The main class of the local implementation of the document api.
To easily obtain an instance of this, with the documents using the schemas (.sd-files) in a given directoy,
use the {@code com.yahoo.vespa.application} test module and {@code DocumentAccesses.ofSchemas(schemaDirectory)}

@author bratseth
@author jonmv
documentapi/src/main/java/com/yahoo/documentapi/local/LocalDocumentAccess.java