code: @Override
      public void evaluate(KnowledgeHelper knowledgeHelper,
              WorkingMemory workingMemory) {
          Proposition prop = (Proposition) workingMemory.getObject(
                  knowledgeHelper.getTuple().get(0));
          List<PropositionCopier> copiers = this.copiersMap.get(prop.getId());
          assert copiers != null : "copiers should never be null";
          for (PropositionCopier copier : copiers) {
              copier.grab(knowledgeHelper);
              prop.accept(copier);
              copier.release();
          }
      }
docs: Uses the <code>inverseIsAPropIdMap</code> to create one or more
  derived propositions from the proposition that fired this rule.
  
  @param knowledgeHelper a {@link KnowledgeHelper}.
  @param workingMemory the {@link WorkingMemory}.