use null as default value

Author: vandonr

tracer/src/Datadog.Trace/RemoteConfigurationManagement/Protocol/RcmClientTracer.cs

@@ -12,7 +12,7 @@ namespace Datadog.Trace.RemoteConfigurationManagement.Protocol
 {
     internal class RcmClientTracer
     {
-        public RcmClientTracer(string runtimeId, string tracerVersion, string service, string env, string? appVersion, List<string> tags, List<string> processTags)
+        public RcmClientTracer(string runtimeId, string tracerVersion, string service, string env, string? appVersion, List<string> tags, List<string>? processTags)
         {
             RuntimeId = runtimeId;
             Language = TracerConstants.Language;
@@ -37,7 +37,7 @@ public RcmClientTracer(string runtimeId, string tracerVersion, string service, s
         public string Service { get; }
 
         [JsonProperty("process_tags")]
-        public List<string> ProcessTags { get; }
+        public List<string>? ProcessTags { get; }
 
         [JsonProperty("extra_services")]
         public string[]? ExtraServices { get; set; }

tracer/src/Datadog.Trace/RemoteConfigurationManagement/RemoteConfigurationManager.cs

@@ -69,7 +69,7 @@ public static RemoteConfigurationManager Create(
             return new RemoteConfigurationManager(
                     discoveryService,
                     remoteConfigurationApi,
-                    new RcmClientTracer(settings.RuntimeId, settings.TracerVersion, serviceName, TraceUtil.NormalizeTag(tracerSettings.Environment), tracerSettings.ServiceVersion, tags, tracerSettings.PropagateProcessTags ? ProcessTags.TagsList : []),
+                    new RcmClientTracer(settings.RuntimeId, settings.TracerVersion, serviceName, TraceUtil.NormalizeTag(tracerSettings.Environment), tracerSettings.ServiceVersion, tags, tracerSettings.PropagateProcessTags ? ProcessTags.TagsList : null),
                     pollInterval: settings.PollInterval,
                     gitMetadataTagsProvider,
                     subscriptionManager);