code: public static ParameterValueStore getInstance(EvaluationContext context) throws IllegalStateException
     {
        ParameterValueStore valueStore = (ParameterValueStore) context.get(ParameterValueStore.class);
        if (valueStore == null)
        {
           throw new IllegalStateException("Could not retrieve " + ParameterValueStore.class.getName() + " from "
                    + EvaluationContext.class.getName() + ". Has the " + EvaluationContext.class.getSimpleName()
                    + " been set up properly?");
        }
        return valueStore;
     }
docs: Retrieve the current {@link ParameterValueStore} from the given {@link EvaluationContext} instance.
  
  @throws IllegalStateException If the {@link ParameterValueStore} could not be located.