add kotlin example

.gitignore

@@ -1,3 +1,5 @@
 *~
 *.key
 *.pem
+.idea
+.local

kotlin_example/.gitignore

@@ -0,0 +1,2 @@
+build
+.gradle

kotlin_example/README.md

@@ -0,0 +1,74 @@
+# Enable Banking API — Kotlin Example
+
+This implementation uses [Spring Boot 4](https://spring.io/projects/spring-boot) with
+[Spring's RestClient](https://docs.spring.io/spring-framework/reference/integration/rest-clients.html)
+for HTTP calls and [Auth0 java-jwt](https://github.com/auth0/java-jwt) for JWT signing.
+
+## Prerequisites
+
+- **JDK 25** — download from [adoptium.net](https://adoptium.net/) or [sdkman.io](https://sdkman.io/)
+- No separate Gradle install needed — the included `./gradlew` wrapper downloads Gradle 9 automatically
+
+## Configuration
+
+Edit `src/main/resources/application.yml` with your application credentials:
+
+```yaml
+enablebanking:
+  key-path: "../<your-app-id>.pem"   # path to your PEM private key, relative to this directory
+  application-id: "<your-app-id>"
+  redirect-url: "http://localhost:8080/auth_redirect"
+```
+
+The `key-path` and `application-id` values come from your application registered at
+[enablebanking.com/cp/applications](https://enablebanking.com/cp/applications).
+
+## Running
+
+### Account information (AIS)
+
+```bash
+./gradlew bootRun --args="--spring.profiles.active=ais"
+```
+
+### Payment initiation (PIS)
+
+```bash
+./gradlew bootRun --args="--spring.profiles.active=pis"
+```
+
+## Authorization flow (AIS)
+
+The account information example includes an interactive consent step:
+
+1. The app prints a bank authorization URL — **open it in your browser**
+2. Log in with your bank credentials and approve the consent
+   - Sandbox credentials: **customera / 12345678**
+3. The bank redirects your browser to the `redirect-url` from `application.yml`
+   (e.g. `http://localhost:8080/auth_redirect?code=...`) — the page may show an error, that is expected
+4. **Copy the full URL** from the browser address bar and paste it into the terminal when prompted
+5. The app extracts the `code` parameter automatically and continues to fetch balances and transactions
+
+## Integrating into an existing Spring Boot 4 service
+
+`EnableBankingService` is a standard `@Service` bean — inject it anywhere:
+
+```kotlin
+@Service
+class YourService(private val enableBanking: EnableBankingService) {
+
+    fun fetchBalances(accountId: String) = enableBanking.getBalances(accountId)
+}
+```
+
+Add the following to your `application.yml`:
+
+```yaml
+enablebanking:
+  key-path: "/path/to/your-key.pem"
+  application-id: "your-application-id"
+  redirect-url: "https://your-redirect-url"
+```
+
+Copy across: `Config.kt`, `Models.kt`, `JwtUtils.kt`, `EnableBankingService.kt`, and add
+`com.auth0:java-jwt:4.4.0` to your dependencies.

kotlin_example/build.gradle.kts

@@ -0,0 +1,42 @@
+plugins {
+    kotlin("jvm") version "2.1.21"
+    kotlin("plugin.spring") version "2.1.21"
+    id("org.springframework.boot") version "4.1.0"
+    id("io.spring.dependency-management") version "1.1.7"
+}
+
+group = "com.enablebanking"
+version = "1.0.0"
+
+java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(25)
+    }
+}
+
+// Kotlin 2.1.x does not yet support JVM target 25; align both compilers to 23
+tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile> {
+    compilerOptions {
+        jvmTarget = org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_23
+    }
+}
+
+tasks.withType<JavaCompile> {
+    sourceCompatibility = "23"
+    targetCompatibility = "23"
+}
+
+repositories {
+    mavenCentral()
+}
+
+tasks.named<org.springframework.boot.gradle.tasks.run.BootRun>("bootRun") {
+    standardInput = System.`in`
+}
+
+dependencies {
+    implementation("org.springframework.boot:spring-boot-starter")
+    implementation("org.springframework.boot:spring-boot-starter-web")
+    implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
+    implementation("com.auth0:java-jwt:4.4.0")
+}

kotlin_example/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.7.0-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

kotlin_example/settings.gradle.kts

@@ -0,0 +1 @@
+rootProject.name = "enablebanking-kotlin-example"