Added serialization

app/build.gradle

@@ -1,7 +1,10 @@
-apply plugin: 'com.android.application'
-apply plugin: 'kotlin-android'
-apply plugin: 'kotlin-android-extensions'
-apply plugin: 'kotlin-kapt'
+plugins {
+    id 'com.android.application'
+    id 'kotlin-android'
+    id 'kotlin-android-extensions'
+    id 'kotlin-kapt'
+    id 'org.jetbrains.kotlin.plugin.serialization' version "$kotlin_version"
+}
 
 def keystorePropertiesFile = rootProject.file("keystore.properties")
 def keystoreProperties = new Properties()
@@ -71,6 +74,7 @@ dependencies {
     implementation 'androidx.swiperefreshlayout:swiperefreshlayout:1.1.0'
     implementation 'com.googlecode.ez-vcard:ez-vcard:0.11.3'
     implementation 'androidx.lifecycle:lifecycle-process:2.5.1'
+    implementation "org.jetbrains.kotlinx:kotlinx-serialization-json:1.4.1"
 
     kapt "androidx.room:room-compiler:2.5.1"
     implementation "androidx.room:room-runtime:2.5.1"

app/src/main/kotlin/com/simplemobiletools/smsmessenger/models/MmsAddress.kt

@@ -4,7 +4,9 @@ import android.content.ContentValues
 import android.provider.Telephony
 import androidx.core.content.contentValuesOf
 import com.google.gson.annotations.SerializedName
+import kotlinx.serialization.Serializable
 
+@Serializable
 data class MmsAddress(
     @SerializedName("address")
     val address: String,

app/src/main/kotlin/com/simplemobiletools/smsmessenger/models/MmsBackup.kt

@@ -4,7 +4,9 @@ import android.content.ContentValues
 import android.provider.Telephony
 import androidx.core.content.contentValuesOf
 import com.google.gson.annotations.SerializedName
+import kotlinx.serialization.Serializable
 
+@Serializable
 data class MmsBackup(
     @SerializedName("creator")
     val creator: String?,

app/src/main/kotlin/com/simplemobiletools/smsmessenger/models/MmsPart.kt

@@ -4,7 +4,9 @@ import android.content.ContentValues
 import android.provider.Telephony
 import androidx.core.content.contentValuesOf
 import com.google.gson.annotations.SerializedName
+import kotlinx.serialization.Serializable
 
+@Serializable
 data class MmsPart(
     @SerializedName("cd")
     val contentDisposition: String?,

app/src/main/kotlin/com/simplemobiletools/smsmessenger/models/SmsBackup.kt

@@ -5,7 +5,9 @@ import android.content.ContentValues
 import android.provider.Telephony
 import androidx.core.content.contentValuesOf
 import com.google.gson.annotations.SerializedName
+import kotlinx.serialization.Serializable
 
+@Serializable
 data class SmsBackup(
     @SerializedName("sub_id")
     val subscriptionId: Long,