While working on https://github.com/square/moshi/pull/1123 I faced an issue where all the models are changed to abstract classes.
And all known issues seems to be closed.

```
@Suppress("MemberNameEqualsClassName")
class Application {
class Property {
@JsonClass(generateAdapter = true, readOnly = false, writeOnly = false)
class Version(
@JvmField val major: Int = 0,
@JvmField val minor: Int = 0,
@JvmField val revision: String = "",
@JvmField val tag: String = ""
)
}
}

```

Generates the adapter
```
// Code generated by moshi-kotlin-codegen. Do not edit.
package com.genimee.android.yatse.mediacenters.kodi.api.model

import com.squareup.moshi.JsonAdapter
import com.squareup.moshi.JsonReader
import com.squareup.moshi.JsonWriter
import com.squareup.moshi.Moshi
import com.squareup.moshi.internal.Util
import java.lang.NullPointerException
import java.lang.reflect.Constructor
import kotlin.Int
import kotlin.String
import kotlin.Suppress
import kotlin.collections.emptySet
import kotlin.jvm.Volatile
import kotlin.text.buildString

@Suppress("DEPRECATION", "unused", "ClassName", "REDUNDANT_PROJECTION", "LocalVariableName")
class Application_Property_VersionJsonAdapter(
moshi: Moshi
) : JsonAdapter<Application.Property.Version>() {
private val options: JsonReader.Options = JsonReader.Options.of("major", "minor", "revision",
"tag")

private val intAdapter: JsonAdapter<Int> = moshi.adapter(Int::class.java, emptySet(), "major")

private val stringAdapter: JsonAdapter<String> = moshi.adapter(String::class.java, emptySet(),
"revision")

@Volatile
private var constructorRef: Constructor<Application.Property.Version>? = null

override fun toString(): String = buildString(50) {
append("GeneratedJsonAdapter(").append("Application.Property.Version").append(')') }

override fun fromJson(reader: JsonReader): Application.Property.Version {
var major: Int? = 0
var minor: Int? = 0
var revision: String? = null
var tag: String? = null
var mask0 = -1
reader.beginObject()
while (reader.hasNext()) {
when (reader.selectName(options)) {
0 -> {
major = intAdapter.fromJson(reader) ?: throw Util.unexpectedNull("major", "major", reader)
// $mask = $mask and (1 shl 0).inv()
mask0 = mask0 and 0xfffffffe.toInt()
}
1 -> {
minor = intAdapter.fromJson(reader) ?: throw Util.unexpectedNull("minor", "minor", reader)
// $mask = $mask and (1 shl 1).inv()
mask0 = mask0 and 0xfffffffd.toInt()
}
2 -> {
revision = stringAdapter.fromJson(reader) ?: throw Util.unexpectedNull("revision",
"revision", reader)
// $mask = $mask and (1 shl 2).inv()
mask0 = mask0 and 0xfffffffb.toInt()
}
3 -> {
tag = stringAdapter.fromJson(reader) ?: throw Util.unexpectedNull("tag", "tag", reader)
// $mask = $mask and (1 shl 3).inv()
mask0 = mask0 and 0xfffffff7.toInt()
}
-1 -> {
// Unknown name, skip it.
reader.skipName()
reader.skipValue()
}
}
}
reader.endObject()
@Suppress("UNCHECKED_CAST")
val localConstructor: Constructor<Application.Property.Version> = this.constructorRef ?:
Application.Property.Version::class.java.getDeclaredConstructor(Int::class.javaPrimitiveType,
Int::class.javaPrimitiveType, String::class.java, String::class.java,
Int::class.javaPrimitiveType, Util.DEFAULT_CONSTRUCTOR_MARKER).also { this.constructorRef =
it }
return localConstructor.newInstance(
major,
minor,
revision,
tag,
mask0,
null
)
}

override fun toJson(writer: JsonWriter, value: Application.Property.Version?) {
if (value == null) {
throw NullPointerException("value was null! Wrap in .nullSafe() to write nullable values.")
}
writer.beginObject()
writer.name("major")
intAdapter.toJson(writer, value.major)
writer.name("minor")
intAdapter.toJson(writer, value.minor)
writer.name("revision")
stringAdapter.toJson(writer, value.revision)
writer.name("tag")
stringAdapter.toJson(writer, value.tag)
writer.endObject()
}
}

```

And the associated R8 rule:
```
-if class com.genimee.android.yatse.mediacenters.kodi.api.model.Application$Property$Version
-keepnames class com.genimee.android.yatse.mediacenters.kodi.api.model.Application$Property$Version
-if class com.genimee.android.yatse.mediacenters.kodi.api.model.Application$Property$Version
-keep class com.genimee.android.yatse.mediacenters.kodi.api.model.Application_Property_VersionJsonAdapter {
public <init>(com.squareup.moshi.Moshi);
}
-if class com.genimee.android.yatse.mediacenters.kodi.api.model.Application$Property$Version
-keepnames class kotlin.jvm.internal.DefaultConstructorMarker
-if class com.genimee.android.yatse.mediacenters.kodi.api.model.Application$Property$Version
-keepclassmembers class com.genimee.android.yatse.mediacenters.kodi.api.model.Application$Property$Version {
public synthetic <init>(int,int,java.lang.String,java.lang.String,int,kotlin.jvm.internal.DefaultConstructorMarker);
}
```

Final bytecode is
```
.class public abstract Lcom/genimee/android/yatse/mediacenters/kodi/api/model/Application$Property$Version;
.super Ljava/lang/Object;
.source "Application.kt"

# annotations
.annotation runtime Lf5/l/a/r;
generateAdapter = true
.end annotation

.annotation runtime Lh5/e;
bv = {
0x1,
0x0,
0x3
}
d1 = {
"\u0000\u0014\n\u0002\u0018\u0002\n\u0002\u0010\u0008\n\u0002\u0008\u0003\n\u0002\u0010\u000e\n\u0002\u0008\u0006\u0008\u0007\u0018\u0000B/\u0012\u0008\u0008\u0002\u0010\u0002\u001a\u00020\u0001\u0012\u0008\u0008\u0002\u0010\u0004\u001a\u00020\u0001\u0012\u0008\u0008\u0002\u0010\u0006\u001a\u00020\u0005\u0012\u0008\u0008\u0002\u0010\u0008\u001a\u00020\u0005\u00a2\u0006\u0004\u0008\t\u0010\nR\u0016\u0010\u0002\u001a\u00020\u00018\u0006@\u0007X\u0087\u0004\u00a2\u0006\u0006\n\u0004\u0008\u0002\u0010\u0003R\u0016\u0010\u0004\u001a\u00020\u00018\u0006@\u0007X\u0087\u0004\u00a2\u0006\u0006\n\u0004\u0008\u0004\u0010\u0003R\u0016\u0010\u0006\u001a\u00020\u00058\u0006@\u0007X\u0087\u0004\u00a2\u0006\u0006\n\u0004\u0008\u0006\u0010\u0007R\u0016\u0010\u0008\u001a\u00020\u00058\u0006@\u0007X\u0087\u0004\u00a2\u0006\u0006\n\u0004\u0008\u0008\u0010\u0007\u00a8\u0006\u000b"
}
d2 = {
"Lcom/genimee/android/yatse/mediacenters/kodi/api/model/Application$Property$Version;",
"",
"major",
"I",
"minor",
"",
"revision",
"Ljava/lang/String;",
"tag",
"<init>",
"(IILjava/lang/String;Ljava/lang/String;)V",
"kodi_release"
}
k = 0x1
mv = {
0x1,
0x1,
0xf
}
pn = ""
xi = 0x0
xs = ""
.end annotation

# direct methods
.method public constructor <init>(IILjava/lang/String;Ljava/lang/String;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
.registers 7

and-int/lit8 p1, p5, 0x1

and-int/lit8 p1, p5, 0x2

and-int/lit8 p1, p5, 0x4

and-int/lit8 p1, p5, 0x8

const/4 p1, 0x0

.line 1
throw p1
.end method

```

So abstract and fails.