code: @Override
      public void visit(Constant constant) {
          assert this.kh != null : "kh wasn't set";
          Constant newConstant = new Constant(propId, this.uniqueIdProvider.getInstance());
          newConstant.setSourceSystem(SourceSystem.DERIVED);
          newConstant.setCreateDate(new Date());
          this.kh.insertLogical(newConstant);
          this.derivationsBuilder.propositionAsserted(constant, newConstant);
          LOGGER.log(Level.FINER, "Asserted derived proposition {0}", newConstant);
      }
docs: Creates a derived constant with the id specified in the
  constructor and the same characteristics (e.g., data source type,
  interval, value, etc.).
  
  @param constant a {@link Constant}. Cannot be <code>null</code>.