[otlp] Use LogRecord.Logger.Name for instrumentation scope if LogRecord.CategoryName is null

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/OtlpLogRecordTransformer.cs

@@ -16,7 +16,9 @@
 
 internal sealed class OtlpLogRecordTransformer
 {
+    private const string DefaultScopeName = "unknown_scope";
+
     internal static readonly ConcurrentBag<OtlpLogs.ScopeLogs> LogListPool = new();
 
     private readonly SdkLimitOptions sdkLimitOptions;
     private readonly ExperimentalOptions experimentalOptions;
@@ -47,10 +49,11 @@
             var otlpLogRecord = this.ToOtlpLog(logRecord);
             if (otlpLogRecord != null)
             {
-                if (!logsByCategory.TryGetValue(logRecord.CategoryName, out var scopeLogs))
+                var scopeName = logRecord.CategoryName ?? logRecord.Logger?.Name ?? DefaultScopeName;
+                if (!logsByCategory.TryGetValue(scopeName, out var scopeLogs))
                 {
-                    scopeLogs = this.GetLogListFromPool(logRecord.CategoryName);
-                    logsByCategory.Add(logRecord.CategoryName, scopeLogs);
+                    scopeLogs = this.GetLogListFromPool(scopeName);
+                    logsByCategory.Add(scopeName, scopeLogs);
                     resourceLogs.ScopeLogs.Add(scopeLogs);
                 }