Prevent the runtime attachment from launching multiple times (#409)

Author: jeanbisutti

runtime-attach/runtime-attach-core/src/main/java/io/opentelemetry/contrib/attach/CoreRuntimeAttach.java

@@ -19,6 +19,8 @@ public final class CoreRuntimeAttach {
 
   private final String agentJarResourceName;
 
+  private boolean runtimeAttachmentRequested;
+
   /**
    * Creates a new {@code DistroRuntimeAttach} from the resource name of the agent jar.
    *
@@ -37,6 +39,11 @@ public void attachJavaagentToCurrentJVM() {
       return;
     }
 
+    if (runtimeAttachmentRequested) {
+      return;
+    }
+    runtimeAttachmentRequested = true;
+
     AgentFileProvider agentFileProvider = new AgentFileProvider(agentJarResourceName);
 
     File javaagentFile = agentFileProvider.getAgentFile();