Don't compare strings to Empty using Equals

Comparing strings using the String.Length property or the String.IsNullOrEmpty method is faster than using Equals. This is because Equals executes significantly more MSIL instructions than either IsNullOrEmpty or the number of instructions executed to retrieve the Length property value and compare it to zero.

.editorconfig

@@ -191,7 +191,6 @@ dotnet_diagnostic.CA1814.severity = suggestion
 dotnet_diagnostic.CA1815.severity = suggestion
 dotnet_diagnostic.CA1816.severity = suggestion
 dotnet_diagnostic.CA1819.severity = suggestion
-dotnet_diagnostic.CA1820.severity = suggestion
 dotnet_diagnostic.CA1822.severity = suggestion
 dotnet_diagnostic.CA1823.severity = suggestion
 dotnet_diagnostic.CA1824.severity = suggestion

src/NzbDrone.Core/Extras/Metadata/Consumers/Xbmc/XbmcMetadata.cs

@@ -239,7 +239,7 @@ namespace NzbDrone.Core.Extras.Metadata.Consumers.Xbmc
                 xmlResult += "https://www.thetvdb.com/?tab=series&id=" + series.TvdbId;
             }
 
-            return xmlResult == string.Empty ? null : new MetadataFileResult("tvshow.nfo", xmlResult);
+            return xmlResult.IsNullOrWhiteSpace() ? null : new MetadataFileResult("tvshow.nfo", xmlResult);
         }
 
         public override MetadataFileResult EpisodeMetadata(Series series, EpisodeFile episodeFile)