chore(build): move to JDK 21 LTS and Kotlin 2.4.21

.github/workflows/kotlin-build.yml

@@ -24,7 +24,7 @@ jobs:
         uses: actions/setup-java@c5195efecf7bdfc987ee8bae7a71cb8b11521c00 # v4.7.1
         with:
           distribution: temurin
-          java-version: "22"
+          java-version: "21"
 
       - name: Set up Android SDK (cmdline)
         uses: android-actions/setup-android@9fc6c4e9069bf8d3d10b2204b1fb8f6ef7065407 # v3.2.2

.github/workflows/version-and-publish.yml

@@ -33,7 +33,7 @@ jobs:
         uses: actions/setup-java@c5195efecf7bdfc987ee8bae7a71cb8b11521c00 # v4.7.1
         with:
           distribution: temurin
-          java-version: "24"
+          java-version: "21"
 
       - name: Set up Android SDK (cmdline)
         uses: android-actions/setup-android@9fc6c4e9069bf8d3d10b2204b1fb8f6ef7065407 # v3.2.2
@@ -96,7 +96,7 @@ jobs:
         uses: actions/setup-java@c5195efecf7bdfc987ee8bae7a71cb8b11521c00 # v4.7.1
         with:
           distribution: temurin
-          java-version: "24"
+          java-version: "21"
 
       - name: Set up Android SDK (cmdline)
         uses: android-actions/setup-android@9fc6c4e9069bf8d3d10b2204b1fb8f6ef7065407 # v3.2.2

README.md

@@ -1,7 +1,7 @@
 # Turnkey Kotlin SDK
 
 [![License: Apache 2.0](https://img.shields.io/badge/License-Apache_2.0-blue?style=flat)](LICENSE)
-[![Static Badge](https://img.shields.io/badge/JVM_toolchain-24-red?style=flat)](https://openjdk.org/projects/jdk/24/)
+[![Static Badge](https://img.shields.io/badge/JDK-21_LTS-red?style=flat)](https://openjdk.org/projects/jdk/21/)
 [![Static Badge](https://img.shields.io/badge/docs-available-008000?style=flat)](https://docs.turnkey.com/sdks/kotlin/overview)
 
 The Turnkey **Kotlin/Android** SDKs provide everything you need to build a fully working Android app powered by Turnkey: typed HTTP access, auth flows (OAuth / Passkeys / OTP), session + key management, and wallet utilities.
@@ -256,7 +256,7 @@ This SDK is designed in layers, allowing you to choose the right level of abstra
 
 ### Requirements
 
-* **JDK/Toolchain:** Kotlin JVM toolchain 24 (see module `kotlin { jvmToolchain(24) }`)
+* **JDK:** 21 (LTS) to run Gradle; modules compile with a Kotlin JVM toolchain of 11 (see `kotlin { jvmToolchain(11) }`)
 * **Android:** compileSdk 36 (for Android modules), minSdk varies per package (e.g., passkey/stamper minSdk 28)
 
 ### Build & test

build.gradle.kts

@@ -12,8 +12,8 @@ plugins {
     id("io.github.gradle-nexus.publish-plugin") version "2.0.0"
     id("com.vanniktech.maven.publish") version "0.34.0" apply false
 
-    kotlin("jvm") version "2.2.20" apply false
-    kotlin("plugin.serialization") version "2.2.20" apply false
+    kotlin("jvm") version "2.4.21" apply false
+    kotlin("plugin.serialization") version "2.4.21" apply false
     alias(libs.plugins.kotlin.android) apply false
     alias(libs.plugins.android.application) apply false
     id("com.android.library") version "8.13.0" apply false

examples/kotlin-demo-wallet/build.gradle.kts

@@ -1,4 +1,5 @@
 import java.util.Properties
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
 
 plugins {
     alias(libs.plugins.android.application)
@@ -61,14 +62,17 @@ android {
         sourceCompatibility = JavaVersion.VERSION_11
         targetCompatibility = JavaVersion.VERSION_11
     }
-    kotlinOptions {
-        jvmTarget = "11"
-    }
     buildFeatures {
         viewBinding = true
     }
 }
 
+kotlin {
+    compilerOptions {
+        jvmTarget.set(JvmTarget.JVM_11)
+    }
+}
+
 dependencies {
     implementation(libs.androidx.core.ktx)
     implementation(libs.androidx.appcompat)

gradle/libs.versions.toml

@@ -15,7 +15,7 @@ material3 = "1.4.0"
 okhttp = "5.1.0"
 swagger-parser = "2.1.34"
 agp = "8.13.0"
-kotlin = "2.2.20"
+kotlin = "2.4.21"
 core-ktx = "1.17.0"
 junit = "4.13.2"
 junit-version = "1.3.0"

packages/tools/build.gradle.kts

@@ -1,5 +1,5 @@
 plugins {
-    kotlin("jvm") version "2.2.20"
+    kotlin("jvm") version "2.4.21"
     application
 }