Adjustments to keep native-image builder happy

Author: mcculls

dd-java-agent/agent-jmxfetch/src/main/java/datadog/trace/agent/jmxfetch/LegacyYaml.java

@@ -0,0 +1,18 @@
+package datadog.trace.agent.jmxfetch;
+
+import java.io.InputStream;
+
+/**
+ * We map the legacy {@code org.yaml.snakeyaml.Yaml} class to this substitute class at build time to
+ * keep the GraalVM native-image builder happy. JmxFetch has a solitary reference to the class, but
+ * it's never called because JMXFetch discovers the embedded snakeyaml-engine library and uses that.
+ */
+public class LegacyYaml {
+  public <T> T load(InputStream in) {
+    throw new UnsupportedOperationException();
+  }
+
+  public String dump(Object data) {
+    throw new UnsupportedOperationException();
+  }
+}

dd-java-agent/build.gradle

@@ -156,6 +156,7 @@ def generalShadowJarConfig(ShadowJar shadowJarTask) {
     // Prevents conflict with other instances, but doesn't relocate instrumentation
     if (!projectName.equals('instrumentation')) {
       relocate 'org.snakeyaml.engine', 'datadog.snakeyaml.engine'
+      relocate 'org.yaml.snakeyaml.Yaml', 'datadog.trace.agent.jmxfetch.LegacyYaml'
       relocate 'okhttp3', 'datadog.okhttp3'
       relocate 'okio', 'datadog.okio'