@Override
 public void endRDF() {
   super.endRDF();
   nullifyBNodes();
 }
 @Override
 protected void buildGraph() {
   super.buildGraph();
   for (QualifiedName contextQ : collators.keySet()) {
     HashMap<QualifiedName, List<Statement>> collator = collators.get(contextQ);
     for (QualifiedName qualifiedName : collator.keySet()) {
       Types.ProvType[] types = getExplicitTypes(contextQ, qualifiedName);
       for (Types.ProvType type : types) {
         switch (type) {
           case GENERATION:
             createGeneration(contextQ, qualifiedName);
             break;
           case USAGE:
             createUsage(contextQ, qualifiedName);
             break;
           case ASSOCIATION:
             createAssociation(contextQ, qualifiedName);
             break;
           case ATTRIBUTION:
             createAttribution(contextQ, qualifiedName);
             break;
           case COMMUNICATION:
             createCommunication(contextQ, qualifiedName);
             break;
           case DELEGATION:
             createDelegation(contextQ, qualifiedName);
             break;
           case DERIVATION:
             createDerivation(
                 contextQ, qualifiedName, onto.QualifiedName_PROVO_qualifiedDerivation);
             break;
           case PRIMARYSOURCE:
             createPrimarySource(contextQ, qualifiedName);
             break;
           case QUOTATION:
             createQuotation(contextQ, qualifiedName);
             break;
           case REVISION:
             createRevision(contextQ, qualifiedName);
             break;
           case END:
             createEnd(contextQ, qualifiedName);
             break;
           case INVALIDATION:
             createInvalidation(contextQ, qualifiedName);
             break;
           case START:
             createStart(contextQ, qualifiedName);
             break;
           case INFLUENCE:
             createInfluence(contextQ, qualifiedName);
             break;
           case INSERTION:
             createInsertion(contextQ, qualifiedName);
             break;
           case REMOVAL:
             createRemoval(contextQ, qualifiedName);
             break;
           default:
             break;
         }
       }
     }
   }
 }