[Backport master] Implement unsigned long numeric field (#5278)

* Implement unsigned long (#5275)

* test fixup

Co-authored-by: Steve Gordon <sgordon@hotmail.co.uk>

Author: github-actions[bot]

src/Nest/Mapping/Types/Core/Number/NumberType.cs

@@ -34,7 +34,10 @@ public enum NumberType
 		Short,
 
 		[EnumMember(Value = "byte")]
-		Byte
+		Byte,
+
+		[EnumMember(Value = "unsigned_long")]
+		UnsignedLong
 	}
 
 	internal static class NumberTypeExtensions
@@ -51,6 +54,7 @@ public static FieldType ToFieldType(this NumberType numberType)
 				case NumberType.Long: return FieldType.Long;
 				case NumberType.Short: return FieldType.Short;
 				case NumberType.Byte: return FieldType.Byte;
+				case NumberType.UnsignedLong: return FieldType.UnsignedLong;
 				default:
 					throw new ArgumentOutOfRangeException(nameof(numberType), numberType, null);
 			}

src/Nest/Mapping/Types/FieldType.cs

@@ -89,6 +89,9 @@ public enum FieldType
 		[EnumMember(Value = "long")]
 		Long,
 
+		[EnumMember(Value = "unsigned_long")]
+		UnsignedLong,
+
 		[EnumMember(Value = "short")]
 		Short,
 

src/Nest/Mapping/Types/PropertyFormatter.cs

@@ -65,6 +65,7 @@ public IProperty Deserialize(ref JsonReader reader, IJsonFormatterResolver forma
 				case FieldType.Long:
 				case FieldType.ScaledFloat:
 				case FieldType.HalfFloat:
+				case FieldType.UnsignedLong:
 					var numberProperty = Deserialize<NumberProperty>(ref segmentReader, formatterResolver);
 					((IProperty)numberProperty).Type = typeString;
 					return numberProperty;

tests/Tests/Mapping/Types/Core/Number/NumberPropertyTests.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information
 
 using System;
+using Elastic.Elasticsearch.Xunit.XunitPlumbing;
 using Nest;
 using Tests.Core.ManagedElasticsearch.Clusters;
 using Tests.Domain;
@@ -112,4 +113,48 @@ public ScaledFloatNumberPropertyTests(WritableCluster cluster, EndpointUsage usa
 			}
 		};
 	}
+
+	[SkipVersion("<7.10.0", "Introduced in 7.10.0")]
+	public class UnsignedLongNumberPropertyTests : PropertyTestsBase
+	{
+		public UnsignedLongNumberPropertyTests(WritableCluster cluster, EndpointUsage usage) : base(cluster, usage) { }
+
+		protected override object ExpectJson => new
+		{
+			properties = new
+			{
+				numberOfCommits = new
+				{
+					type = "unsigned_long",
+					doc_values = true,
+					store = true,
+					index = false,
+					ignore_malformed = true
+				}
+			}
+		};
+
+		protected override Func<PropertiesDescriptor<Project>, IPromise<IProperties>> FluentProperties => f => f
+			.Number(n => n
+				.Name(p => p.NumberOfCommits)
+				.Type(NumberType.UnsignedLong)
+				.DocValues()
+				.Store()
+				.Index(false)
+				.IgnoreMalformed()
+			);
+		
+		protected override IProperties InitializerProperties => new Properties
+		{
+			{
+				"numberOfCommits", new NumberProperty(NumberType.UnsignedLong)
+				{
+					DocValues = true,
+					Store = true,
+					Index = false,
+					IgnoreMalformed = true
+				}
+			}
+		};
+	}
 }