Create overload that internal unix timestamp can be used

src/Elastic.Apm/Helpers/TimeUtils.cs

@@ -6,15 +6,15 @@
 
 namespace Elastic.Apm.Helpers
 {
-	public static class TimeUtils
+	internal static class TimeUtils
 	{
 		/// <summary>
 		/// DateTime.UnixEpoch Field does not exist in .NET Standard 2.0
 		/// https://docs.microsoft.com/en-us/dotnet/api/system.datetime.unixepoch
 		/// </summary>
 		internal static readonly DateTime UnixEpochDateTime = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
 
-		public static long TimestampNow() => ToTimestamp(DateTime.UtcNow);
+		internal static long TimestampNow() => ToTimestamp(DateTime.UtcNow);
 
 		/// <summary>
 		/// UTC based and formatted as microseconds since Unix epoch.

src/Elastic.Apm/Metrics/MetricSet.cs

@@ -4,6 +4,7 @@
 
 using System.Collections.Generic;
 using Elastic.Apm.Api;
+using Elastic.Apm.Helpers;
 using Elastic.Apm.Report.Serialization;
 using Newtonsoft.Json;
 
@@ -12,6 +13,9 @@ namespace Elastic.Apm.Metrics
 	[JsonConverter(typeof(MetricSetConverter))]
 	public class MetricSet : IMetricSet
 	{
+		public MetricSet(IEnumerable<MetricSample> samples)
+			: this(TimeUtils.TimestampNow(), samples)  { }
+
 		public MetricSet(long timestamp, IEnumerable<MetricSample> samples)
 			=> (Timestamp, Samples) = (timestamp, samples);
 

src/Elastic.Apm/Metrics/MetricsCollector.cs

@@ -168,7 +168,7 @@ private void CollectAllMetricsImpl()
 				return;
 			}
 
-			var metricSet = new MetricSet(TimeUtils.TimestampNow(), samplesFromAllProviders);
+			var metricSet = new MetricSet(samplesFromAllProviders);
 
 			try
 			{