target java 1.8

Author: hauner

build.gradle

@@ -59,10 +59,15 @@ compileTestGroovy {
     classpath += files(compileKotlin.destinationDir)
 }
 
+compileKotlin {
+    kotlinOptions.jvmTarget = "1.8"
+}
+
 dependencies {
     implementation 'org.codehaus.groovy:groovy:2.5.10'
     implementation 'org.codehaus.groovy:groovy-nio:2.5.10'
-    implementation 'org.jetbrains.kotlin:kotlin-stdlib'
+    implementation 'org.jetbrains.kotlin:kotlin-stdlib-jdk8'
+
     implementation ('io.swagger.parser.v3:swagger-parser:2.0.19') {
         exclude group: 'io.swagger.parser.v3', module: 'swagger-parser-v2-converter'
         exclude group: 'io.swagger.core.v3', module: 'swagger-annotations'