code: function create (id, spec) {
    // create an entity instance
    const entity = new RenderTemplate()
    entity.spec = spec
    // set/create template from spec.template value
    entity.template = _.template(_.defaultTo(spec.template, ''))
    return entity
  }
docs: Entity Factory
  @param {string} id - Entity id
  @param {*} spec - Entity Specification
  @return {RenderTemplate} RenderTemplate Instance