Use sent_at instead of sentry_timestamp to reduce clock skew

CHANGELOG.md

@@ -6,7 +6,8 @@
 
 - Improve timestamp precision of transactions and spans ([#1680](https://github.com/getsentry/sentry-dotnet/pull/1680))
 - Flatten AggregateException ([#1672](https://github.com/getsentry/sentry-dotnet/pull/1672))
-  - NOTE: This can affect grouping. You can keep the original behavior by setting the option `KeepAggregateException` to `true`.  
+  - NOTE: This can affect grouping. You can keep the original behavior by setting the option `KeepAggregateException` to `true`. 
+- Add sent_at to event ([#1690](https://github.com/getsentry/sentry-dotnet/pull/1690)) 
 
 ### Features
 

src/Sentry/SentryEvent.cs

@@ -229,6 +229,7 @@ public void WriteTo(Utf8JsonWriter writer, IDiagnosticLogger? logger)
             writer.WriteStringDictionaryIfNotEmpty("modules", _modules!);
             writer.WriteSerializable("event_id", EventId, logger);
             writer.WriteString("timestamp", Timestamp);
+            writer.WriteString("sent_at", DateTimeOffset.UtcNow);
             writer.WriteSerializableIfNotNull("logentry", Message, logger);
             writer.WriteStringIfNotWhiteSpace("logger", Logger);
             writer.WriteString("platform", Constants.Platform);

test/Sentry.Tests/Protocol/SentryEventTests.SerializeObject_AllPropertiesSetToNonDefault_SerializesValidObject.verified.txt

@@ -0,0 +1,90 @@
+{
+  breadcrumbs: [
+    {
+      message: crumb,
+      timestamp: Date_MaxValue
+    },
+    {
+      category: category,
+      data: {
+        data-key: data-value
+      },
+      level: warning,
+      message: message,
+      timestamp: Date_MaxValue,
+      type: type
+    }
+  ],
+  contexts: {
+    .NET Framework: {
+      .NET Framework: "v2.0.50727", "v3.0", "v3.5",
+      .NET Framework Client: "v4.8", "v4.0.0.0",
+      .NET Framework Full: "v4.8"
+    },
+    context_key: context_value
+  },
+  debug_meta: {
+    images: [
+      {
+        debug_id: Guid_1,
+        type: wasm
+      }
+    ]
+  },
+  environment: environment,
+  event_id: Guid_2,
+  exception: {
+    values: [
+      {
+        value: exception_value
+      }
+    ]
+  },
+  extra: {
+    extra_key: extra_value
+  },
+  fingerprint: [
+    fingerprint
+  ],
+  level: fatal,
+  logentry: {
+    formatted: structured_message,
+    message: message
+  },
+  logger: logger,
+  modules: {
+    module_key: module_value
+  },
+  platform: csharp,
+  release: release,
+  request: {
+    method: POST
+  },
+  sdk: {
+    name: SDK-test,
+    packages: [
+      {
+        name: name,
+        version: version
+      }
+    ],
+    version: 1.1.1
+  },
+  sent_at: DateTime_1,
+  server_name: server_name,
+  tags: {
+    tag_key: tag_value
+  },
+  threads: {
+    values: [
+      {
+        crashed: true
+      }
+    ]
+  },
+  timestamp: Date_MaxValue,
+  transaction: transaction,
+  user: {
+    id: user-id
+  }
+}

test/Sentry.Tests/Protocol/SentryEventTests.cs

@@ -1,9 +1,10 @@
 namespace Sentry.Tests.Protocol;
 
+[UsesVerify]
 public class SentryEventTests
 {
     [Fact]
-    public void SerializeObject_AllPropertiesSetToNonDefault_SerializesValidObject()
+    public async Task SerializeObject_AllPropertiesSetToNonDefault_SerializesValidObject()
     {
         var ex = new Exception("exception message");
         var timestamp = DateTimeOffset.MaxValue;
@@ -59,6 +60,8 @@ public void SerializeObject_AllPropertiesSetToNonDefault_SerializesValidObject()
 
         var actualString = sut.ToJsonString();
 
+        await VerifyJson(actualString);
+
         actualString.Should().Contain(
             "\"debug_meta\":{\"images\":[" +
             "{\"type\":\"wasm\",\"debug_id\":\"900f7d1b868432939de4457478f34720\"}" +