Shipment/Model/ShipmentStates.php
static public function getStates()
    {
        return [
            static::STATE_NEW,
            static::STATE_CANCELED,
            static::STATE_PREPARATION,
            static::STATE_READY,
            static::STATE_SHIPPED,
            static::STATE_PENDING,
            static::STATE_RETURNED,
            static::STATE_NONE,
            static::STATE_PARTIAL,
            static::STATE_COMPLETED,
        ];
    }
static public function getStates()
    {
        return [
            static::STATE_NEW,
            static::STATE_CANCELED,
            static::STATE_PREPARATION,
            static::STATE_READY,
            static::STATE_SHIPPED,
            static::STATE_PENDING,
            static::STATE_RETURNED,
            static::STATE_NONE,
            static::STATE_PARTIAL,
            static::STATE_COMPLETED,
        ];
    }
Returns all the states.

@return array