From 11c506e0add7e55bab982e56974a61a0e36e73f8 Mon Sep 17 00:00:00 2001
From: Paulo Janotti <pjanotti@splunk.com>
Date: Thu, 23 Sep 2021 13:08:44 -0700
Subject: [PATCH] Fix null exception on PropagationHelpers (#142)

---
 tracer/src/Datadog.Trace/Propagation/PropagationHelpers.cs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tracer/src/Datadog.Trace/Propagation/PropagationHelpers.cs b/tracer/src/Datadog.Trace/Propagation/PropagationHelpers.cs
index ce7b05565..730f317ec 100644
--- a/tracer/src/Datadog.Trace/Propagation/PropagationHelpers.cs
+++ b/tracer/src/Datadog.Trace/Propagation/PropagationHelpers.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Datadog.Trace.Conventions;
 using Datadog.Trace.Logging;
 
@@ -9,7 +10,7 @@ internal static class PropagationHelpers
     {
         public static TraceId ParseTraceId<T>(T carrier, Func<T, string, IEnumerable<string>> getter, string headerName, ITraceIdConvention traceIdConvention, IDatadogLogger logger)
         {
-            var headerValues = getter(carrier, headerName);
+            var headerValues = getter(carrier, headerName) ?? Enumerable.Empty<string>();
 
             foreach (var headerValue in headerValues)
             {
@@ -28,7 +29,7 @@ public static TraceId ParseTraceId<T>(T carrier, Func<T, string, IEnumerable<str
 
         public static string ParseString<T>(T carrier, Func<T, string, IEnumerable<string>> getter, string headerName)
         {
-            var headerValues = getter(carrier, headerName);
+            var headerValues = getter(carrier, headerName) ?? Enumerable.Empty<string>();
 
             foreach (var headerValue in headerValues)
             {