type CustomEnum string

const (
    EnumA CustomEnum = "A"
    EnumB CustomEnum = "B"
    EnumC CustomEnum = "C"
)

type MyForm struct {
    Something bool `json:"something"`
    HereTheProblem []CustomEnum `json:"here_the_problem"`
}

// MyHandler godoc
// @Summary     Just a handler
// @Description Handler description
// @Tags        handler
// @ID          unique-id_oh_yeah
// @Produce     json
// @Param       data        query    MyForm true "filters"
// @Success     200         {object} SomeReturnStruct
// @Success     404         {object} dtos.Errors
// @Success     500         {object} dtos.Errors
// @Security    Token
// @Router      /myhandler [get]
func MyHandler(c *fiber.Ctx) error {
     // doesn't matters
    return nil
}