Replace helper implementation with DateOffset members

Author: bording

LibGit2Sharp/Core/Epoch.cs

@@ -7,30 +7,20 @@ namespace LibGit2Sharp.Core
     /// </summary>
     internal static class Epoch
     {
-        private static readonly DateTimeOffset epochDateTimeOffset = new DateTimeOffset(1970, 1, 1, 0, 0, 0, TimeSpan.Zero);
-
         /// <summary>
         /// Builds a <see cref="DateTimeOffset"/> from a Unix timestamp and a timezone offset.
         /// </summary>
         /// <param name="secondsSinceEpoch">The number of seconds since 00:00:00 UTC on 1 January 1970.</param>
         /// <param name="timeZoneOffsetInMinutes">The number of minutes from UTC in a timezone.</param>
         /// <returns>A <see cref="DateTimeOffset"/> representing this instant.</returns>
-        public static DateTimeOffset ToDateTimeOffset(long secondsSinceEpoch, int timeZoneOffsetInMinutes)
-        {
-            DateTimeOffset utcDateTime = epochDateTimeOffset.AddSeconds(secondsSinceEpoch);
-            TimeSpan offset = TimeSpan.FromMinutes(timeZoneOffsetInMinutes);
-            return new DateTimeOffset(utcDateTime.DateTime.Add(offset), offset);
-        }
+        public static DateTimeOffset ToDateTimeOffset(long secondsSinceEpoch, int timeZoneOffsetInMinutes) =>
+            DateTimeOffset.FromUnixTimeSeconds(secondsSinceEpoch).ToOffset(TimeSpan.FromMinutes(timeZoneOffsetInMinutes));
 
         /// <summary>
         /// Converts the<see cref="DateTimeOffset.UtcDateTime"/> part of a <see cref="DateTimeOffset"/> into a Unix timestamp.
         /// </summary>
         /// <param name="date">The <see cref="DateTimeOffset"/> to convert.</param>
         /// <returns>The number of seconds since 00:00:00 UTC on 1 January 1970.</returns>
-        public static Int32 ToSecondsSinceEpoch(this DateTimeOffset date)
-        {
-            DateTimeOffset utcDate = date.ToUniversalTime();
-            return (Int32)utcDate.Subtract(epochDateTimeOffset).TotalSeconds;
-        }
+        public static Int32 ToSecondsSinceEpoch(this DateTimeOffset date) => (int)date.ToUnixTimeSeconds();
     }
 }