Use data object for non-expiry mode (#12)

Author: SessionHero01

library/src/main/java/network/loki/messenger/libsession_util/util/ExpiryMode.kt

@@ -3,7 +3,7 @@ package network.loki.messenger.libsession_util.util
 import kotlin.time.Duration.Companion.seconds
 
 sealed class ExpiryMode(val expirySeconds: Long) {
-    object NONE: ExpiryMode(0)
+    data object NONE: ExpiryMode(0)
     data class AfterSend(private val seconds: Long = 0L): ExpiryMode(seconds)
     data class AfterRead(private val seconds: Long = 0L): ExpiryMode(seconds)
 
@@ -14,4 +14,4 @@ sealed class ExpiryMode(val expirySeconds: Long) {
     fun coerceSendToRead(coerce: Boolean = true) = if (coerce && this is AfterSend) AfterRead(expirySeconds) else this
 }
 
-fun afterSend(seconds: Long) = seconds.takeIf { it > 0 }?.let(ExpiryMode::AfterSend) ?: ExpiryMode.NONE
+fun afterSend(seconds: Long) = seconds.takeIf { it > 0 }?.let(ExpiryMode::AfterSend) ?: ExpiryMode.NONE