func NewObserver(notifier Notifier) *Observer {
	return &Observer{notifier: notifier}
}
NewObserver returns observer.
package webnotifier
import (
	"encoding/json"
	"github.com/hyperledger/aries-framework-go/pkg/didcomm/common/service"
)
const (
	preState  = "pre_state"
	postState = "post_state"
)
type Notifier interface {
	Notify(topic string, message []byte) error
}
type Observer struct {
	notifier Notifier
}