docs: private Attribute<D> putInstance(Schema.BaseType instanceBaseType, Supplier<Attribute<D>> finder, BiFunction<VertexElement, AttributeType<D>, Attribute<D>> producer, boolean isInferred) {
          Attribute<D> instance = finder.get();
          if (instance == null) {
              instance = addInstance(instanceBaseType, producer, isInferred);
          } else {
              if (isInferred && !instance.isInferred()) {
                  throw TransactionException.nonInferredThingExists(instance);
              }
          }
          return instance;
      }