Add missing parameter to date range aggregation method (Port of #4024)

(cherry picked from commit d7c2e83)

src/Nest/Aggregations/Bucket/DateRange/DateRangeAggregation.cs

@@ -17,6 +17,9 @@ public interface IDateRangeAggregation : IBucketAggregation
 		[DataMember(Name ="format")]
 		string Format { get; set; }
 
+		[DataMember(Name="missing")]
+		object Missing { get; set; }
+
 		[DataMember(Name ="ranges")]
 		IEnumerable<IDateRangeExpression> Ranges { get; set; }
 
@@ -32,6 +35,7 @@ public DateRangeAggregation(string name) : base(name) { }
 
 		public Field Field { get; set; }
 		public string Format { get; set; }
+		public object Missing { get; set; }
 		public IEnumerable<IDateRangeExpression> Ranges { get; set; }
 		public string TimeZone { get; set; }
 
@@ -47,6 +51,8 @@ public class DateRangeAggregationDescriptor<T>
 
 		string IDateRangeAggregation.Format { get; set; }
 
+		object IDateRangeAggregation.Missing { get; set; }
+
 		IEnumerable<IDateRangeExpression> IDateRangeAggregation.Ranges { get; set; }
 
 		string IDateRangeAggregation.TimeZone { get; set; }
@@ -57,6 +63,8 @@ public class DateRangeAggregationDescriptor<T>
 
 		public DateRangeAggregationDescriptor<T> Format(string format) => Assign(format, (a, v) => a.Format = v);
 
+		public DateRangeAggregationDescriptor<T> Missing(object missing) => Assign(missing, (a, v) => a.Missing = v);
+
 		public DateRangeAggregationDescriptor<T> Ranges(params IDateRangeExpression[] ranges) =>
 			Assign(ranges.ToListOrNullIfEmpty(), (a, v) => a.Ranges = v);