From c86a2af78c87bab225a30dab0b765930324d929b Mon Sep 17 00:00:00 2001
From: Sergei Malafeev <sergeymalafeev@gmail.com>
Date: Fri, 29 May 2020 06:08:31 +0800
Subject: [PATCH] #425 allow only one propagator per concern (#451)

---
 .../opentelemetry/auto/tooling/PropagatorsInitializer.java | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/agent-tooling/src/main/java/io/opentelemetry/auto/tooling/PropagatorsInitializer.java b/agent-tooling/src/main/java/io/opentelemetry/auto/tooling/PropagatorsInitializer.java
index a04ebe304760..d37c7309b608 100644
--- a/agent-tooling/src/main/java/io/opentelemetry/auto/tooling/PropagatorsInitializer.java
+++ b/agent-tooling/src/main/java/io/opentelemetry/auto/tooling/PropagatorsInitializer.java
@@ -44,11 +44,18 @@ public static void initializePropagators(List<String> propagators) {
 
     DefaultContextPropagators.Builder propagatorsBuilder = DefaultContextPropagators.builder();
 
+    boolean addedPropagator = false;
     for (String propagatorId : propagators) {
       HttpTextFormat textPropagator = TEXTMAP_PROPAGATORS.get(propagatorId.trim().toLowerCase());
       if (textPropagator != null) {
+        if (addedPropagator) {
+          log.warn(
+              "Only one propagator per concern can be added, " + textPropagator + " is ignored");
+          continue;
+        }
         propagatorsBuilder.addHttpTextFormat(textPropagator);
         log.info("Added " + textPropagator + " propagator");
+        addedPropagator = true;
       } else {
         log.warn("No matching propagator for " + propagatorId);
       }