code: @Override
      public AnchorVariableSupply createExternalizedSupply(InnerScoreDirector scoreDirector) {
          SingletonInverseVariableSupply inverseVariableSupply = scoreDirector.getSupplyManager()
                  .demand(new SingletonInverseVariableDemand(sourceVariableDescriptor));
          return new ExternalizedAnchorVariableSupply(sourceVariableDescriptor, inverseVariableSupply);
      }
docs: ************************************************************************