gradle build settings tweak to avoid jdk version conflict

compilerInterfaces/build.gradle

@@ -11,6 +11,18 @@ java {
     }
 }
 
+compileKotlin {
+    kotlinOptions {
+        jvmTarget = javaVersion
+    }
+}
+
+compileTestKotlin {
+    kotlinOptions {
+        jvmTarget = javaVersion
+    }
+}
+
 dependencies {
     implementation project(':compilerAst')
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"