IAP module refactor, Kotlin 2, Compose (#2)

## Refactor

- Initialize billing via `initBillingClient`
- Add `ProductManager` caching
- Strengthen `fetchProducts` and `requestPurchase`
- Expose:
  - `getAvailableItems(type)`
  - `getStorefront`
- Move private helpers below public API
- Remove `ExpoMapMappers` in favor of model `toJSON`

## Upgrade

- Upgrade to Kotlin **2.0.21**
- Enable Kotlin Compose plugin in **app** and **library**
- Align to **Java 17**
- Remove deprecated `targetSdk` in library

Author: hyochan

Example/build.gradle.kts

@@ -1,6 +1,7 @@
 plugins {
     id("com.android.application")
     id("org.jetbrains.kotlin.android")
+    id("org.jetbrains.kotlin.plugin.compose")
 }
 
 android {
@@ -33,23 +34,18 @@ android {
     }
 
     compileOptions {
-        sourceCompatibility = JavaVersion.VERSION_11
-        targetCompatibility = JavaVersion.VERSION_11
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
     }
 
     kotlinOptions {
-        jvmTarget = "11"
+        jvmTarget = "17"
     }
 
     buildFeatures {
         compose = true
     }
 
-    composeOptions {
-        kotlinCompilerExtensionVersion =
-            (project.findProperty("COMPOSE_COMPILER_VERSION") as String?) ?: "1.5.14"
-    }
-
     packaging {
         resources {
             excludes += "/META-INF/{AL2.0,LGPL2.1}"
@@ -81,4 +77,3 @@ dependencies {
     androidTestImplementation("androidx.test.espresso:espresso-core:3.5.1")
     androidTestImplementation("androidx.compose.ui:ui-test-junit4:$composeUiVersion")
 }
-

build.gradle.kts

@@ -1,7 +1,8 @@
 plugins {
     id("com.android.library") version "8.5.0" apply false
     id("com.android.application") version "8.5.0" apply false
-    id("org.jetbrains.kotlin.android") version "1.9.24" apply false
+    id("org.jetbrains.kotlin.android") version "2.0.21" apply false
+    id("org.jetbrains.kotlin.plugin.compose") version "2.0.21" apply false
     id("com.vanniktech.maven.publish") version "0.29.0" apply false
 }
 

openiap/build.gradle.kts

@@ -1,6 +1,7 @@
 plugins {
     id("com.android.library")
     id("org.jetbrains.kotlin.android")
+    id("org.jetbrains.kotlin.plugin.compose")
     id("com.vanniktech.maven.publish")
 }
 
@@ -16,7 +17,6 @@ android {
 
     defaultConfig {
         minSdk = 21
-        targetSdk = 34
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
         consumerProguardFiles("consumer-rules.pro")
@@ -33,31 +33,26 @@ android {
     }
 
     compileOptions {
-        sourceCompatibility = JavaVersion.VERSION_11
-        targetCompatibility = JavaVersion.VERSION_11
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
     }
 
     kotlinOptions {
-        jvmTarget = "11"
+        jvmTarget = "17"
     }
 
     // Enable Compose for composables in this library (IapContext)
     buildFeatures {
         compose = true
     }
-
-    composeOptions {
-        kotlinCompilerExtensionVersion =
-            (project.findProperty("COMPOSE_COMPILER_VERSION") as String?) ?: "1.5.14"
-    }
 }
 
 dependencies {
     implementation("androidx.core:core-ktx:1.12.0")
     implementation("androidx.lifecycle:lifecycle-runtime-ktx:2.7.0")
 
-    // Google Play Billing Library
-    api("com.android.billingclient:billing-ktx:6.0.1")
+    // Google Play Billing Library (align with app/lib v8)
+    api("com.android.billingclient:billing-ktx:8.0.0")
 
     // Kotlin Coroutines
     implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.7.3")

openiap/src/main/java/dev/hyo/openiap/OpenIapError.kt

@@ -9,6 +9,12 @@ sealed class OpenIapError : Exception() {
     abstract val code: String
     abstract override val message: String
 
+    fun toJSON(): Map<String, Any?> = mapOf(
+        "code" to toCode(this),
+        "message" to (this.message ?: ""),
+        "platform" to "android",
+    )
+
     data class ProductNotFound(val productId: String) : OpenIapError() {
         override val code = "PRODUCT_NOT_FOUND"
         override val message = "Product not found: $productId"