Make all JNI wrappers target Java 8

Author: sstone

build.gradle.kts

@@ -44,6 +44,11 @@ kotlin {
         }
     }
 
+    java {
+        sourceCompatibility = JavaVersion.VERSION_1_8
+        targetCompatibility = JavaVersion.VERSION_1_8
+    }
+
     fun KotlinNativeTarget.secp256k1CInterop(target: String) {
         compilations["main"].cinterops {
             val libsecp256k1 by creating {

jni/jvm/build.gradle.kts

@@ -41,6 +41,7 @@ kotlin {
 
 java {
     sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
 }
 
 publishing {

jni/jvm/darwin/build.gradle.kts

@@ -1,10 +1,23 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
 plugins {
     kotlin("jvm")
     `java-library`
     id("org.jetbrains.dokka")
     `maven-publish`
 }
 
+kotlin {
+    compilerOptions {
+        jvmTarget.set(JvmTarget.JVM_1_8)
+    }
+}
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
+}
+
 dependencies {
     implementation(project(":jni:jvm"))
 }

jni/jvm/linux/build.gradle.kts

@@ -1,9 +1,22 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
 plugins {
     kotlin("jvm")
     id("org.jetbrains.dokka")
     `maven-publish`
 }
 
+kotlin {
+    compilerOptions {
+        jvmTarget.set(JvmTarget.JVM_1_8)
+    }
+}
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
+}
+
 dependencies {
     implementation(project(":jni:jvm"))
 }