Merge pull request #2172 from newrelic/detect-scala3-source

Add scala3 source detection

newrelic-agent/src/main/java/com/newrelic/agent/language/SourceLibraryDetector.java

@@ -59,6 +59,7 @@ public boolean isDone() {
     void detectSourceLanguages() {
         ClassLoader systemClassLoader = ClassLoader.getSystemClassLoader();
         detectJava();
+        detectScala3(systemClassLoader);
         detectScala(systemClassLoader);
         detectKotlin(systemClassLoader);
         detectClojure(systemClassLoader);
@@ -89,9 +90,25 @@ private void detectJava() {
         }
     }
 
+    private void detectScala3(ClassLoader systemClassLoader) {
+        try {
+            //scala3-library removed all methods referencing the version 3 number, so we only capture the major version
+            //by checking for a class introduced in the scala 3 API.
+            Class<?> aClass = Class.forName("scala.deriving.Mirror", true, systemClassLoader);
+            if (aClass != null) {
+                recordSourceLanguageMetric("scala", "3.x");
+            }
+        } catch (ClassNotFoundException cnfe){
+            Agent.LOG.log(Level.FINEST, format("Class ''{0}'' was not found; scala3 is not present in the classpath", "scala.deriving.Mirror"));
+        } catch (Exception e) {
+            Agent.LOG.log(Level.FINEST, format("Exception occurred while trying to determine scala3 version", e.getMessage()));
+        }
+    }
+
     private void detectScala(ClassLoader systemClassLoader) {
         try {
-            // Scala has a static versionNumberString method that can be invoked to get the version number
+            // Scala has a static versionNumberString method that can be invoked to get the version number.
+            // A scala 3 app will also capture this metric, because scala 3 includes the scala 2.13 library.
             Class<?> aClass = Class.forName(SCALA_VERSION_CLASS, true, systemClassLoader);
             if (aClass != null) {
                 String version = (String) aClass.getMethod(SCALA_VERSION_METHOD).invoke(null);