add mavenCentral to plugin repos

dd-java-agent/instrumentation/instrumentation.gradle

@@ -1,5 +1,10 @@
 // this project will run in isolation under the agent's classloader
 buildscript {
+  
+  repositories {
+    mavenCentral()
+  }
+  
   dependencies {
     classpath "net.bytebuddy:byte-buddy-gradle-plugin:${versions.bytebuddy}"
     classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:${versions.kotlin}"

gradle/test-with-kotlin.gradle

@@ -1,6 +1,12 @@
 // Enable testing kotlin code in groovy spock tests.
 apply plugin: 'kotlin'
 
+kotlin {
+  //This option prevents compilation issues when switching branches while refactoring java code to kotlin.
+  //After we are done refactoring java -> kotlin when can disable this and use gradle build cache features.
+  copyClassesToJavaOutput = true
+}
+
 compileTestGroovy {
   classpath = classpath.plus(files(compileTestKotlin.destinationDir))
   dependsOn compileTestKotlin