code: func (c corsWrapper) build() gin.HandlerFunc {
  	return func(ctx *gin.Context) {
  		c.HandlerFunc(ctx.Writer, ctx.Request)
  		if !c.optionPassthrough &&
  			ctx.Request.Method == http.MethodOptions &&
  			ctx.GetHeader("Access-Control-Request-Method") != "" {
  			// Abort processing next Gin middlewares.
  			ctx.AbortWithStatus(http.StatusOK)
  		}
  	}
  }
docs: // build transforms wrapped cors.Cors handler into Gin middleware.