code: function create (id, spec) {
    validateModifiers(id, spec, ['schema', 'options'])
  
    const entity = {}
    entity.spec = spec
    entity.schema = deepFreeze(_.defaultTo(spec.schema, {}))
    entity.options = deepFreeze(_.defaultTo(spec.options, {}))
  
    validateSchema(entity.schema, entity.options)
    return entity
  }
docs: Creates new Entity Object
  @param {Object} spec - spec
  @param {string} id - Entity id
  @throws if spec.schema is not a valid ajv schema
  @return {Object} Entity Object