fix #3326 Add index_prefixes to Text property mapping

src/Nest/Mapping/Types/Core/Text/TextAttribute.cs

@@ -17,6 +17,7 @@ public TextAttribute() : base(FieldType.Text) { }
 		bool? ITextProperty.EagerGlobalOrdinals { get; set; }
 		bool? ITextProperty.Fielddata { get; set; }
 		IFielddataFrequencyFilter ITextProperty.FielddataFrequencyFilter { get; set; }
+		ITextIndexPrefixes ITextProperty.IndexPrefixes { get; set; }
 		bool? ITextProperty.Index { get; set; }
 		IndexOptions? ITextProperty.IndexOptions { get; set; }
 		bool? ITextProperty.Norms { get; set; }

src/Nest/Mapping/Types/Core/Text/TextIndexPrefixes.cs

@@ -0,0 +1,32 @@
+using Newtonsoft.Json;
+
+namespace Nest
+{
+	[JsonObject(MemberSerialization.OptIn)]
+	[JsonConverter(typeof(ReadAsTypeJsonConverter<TextIndexPrefixes>))]
+	public interface ITextIndexPrefixes
+	{
+		[JsonProperty("min_chars")]
+		int? MinCharacters { get; set; }
+
+		[JsonProperty("max_chars")]
+		int? MaxCharacters { get; set; }
+	}
+
+	public class TextIndexPrefixes : ITextIndexPrefixes
+	{
+		public int? MinCharacters { get; set; }
+		public int? MaxCharacters { get; set; }
+	}
+
+	public class TextIndexPrefixesDescriptor
+		: DescriptorBase<TextIndexPrefixesDescriptor, ITextIndexPrefixes>, ITextIndexPrefixes
+	{
+		int? ITextIndexPrefixes.MinCharacters { get; set; }
+		int? ITextIndexPrefixes.MaxCharacters { get; set; }
+
+		public TextIndexPrefixesDescriptor MinCharacters(int? min) => Assign(a => a.MinCharacters = min);
+
+		public TextIndexPrefixesDescriptor MaxCharacters(int? max) => Assign(a => a.MaxCharacters = max);
+	}
+}

src/Nest/Mapping/Types/Core/Text/TextProperty.cs

@@ -28,6 +28,9 @@ public interface ITextProperty : ICoreProperty
 		[JsonProperty("fielddata_frequency_filter")]
 		IFielddataFrequencyFilter FielddataFrequencyFilter { get; set; }
 
+		[JsonProperty("index_prefixes")]
+		ITextIndexPrefixes IndexPrefixes { get; set; }
+
 		[JsonProperty("index")]
 		bool? Index { get; set; }
 
@@ -53,6 +56,7 @@ public TextProperty() : base(FieldType.Text) { }
 		public bool? EagerGlobalOrdinals { get; set; }
 		public bool? Fielddata { get; set; }
 		public IFielddataFrequencyFilter FielddataFrequencyFilter { get; set; }
+		public ITextIndexPrefixes IndexPrefixes { get; set; }
 		public bool? Index { get; set; }
 		public IndexOptions? IndexOptions { get; set; }
 		public bool? Norms { get; set; }
@@ -72,6 +76,7 @@ public class TextPropertyDescriptor<T>
 		bool? ITextProperty.EagerGlobalOrdinals { get; set; }
 		bool? ITextProperty.Fielddata { get; set; }
 		IFielddataFrequencyFilter ITextProperty.FielddataFrequencyFilter { get; set; }
+		ITextIndexPrefixes ITextProperty.IndexPrefixes { get; set; }
 		bool? ITextProperty.Index { get; set; }
 		IndexOptions? ITextProperty.IndexOptions { get; set; }
 		bool? ITextProperty.Norms { get; set; }
@@ -88,6 +93,8 @@ public TextPropertyDescriptor() : base(FieldType.Text) { }
  		public TextPropertyDescriptor<T> Fielddata(bool? fielddata = true) => Assign(a => a.Fielddata = fielddata);
 		public TextPropertyDescriptor<T> FielddataFrequencyFilter(Func<FielddataFrequencyFilterDescriptor, IFielddataFrequencyFilter> selector) =>
 			Assign(a => a.FielddataFrequencyFilter = selector?.Invoke(new FielddataFrequencyFilterDescriptor()));
+		public TextPropertyDescriptor<T> IndexPrefixes(Func<TextIndexPrefixesDescriptor, ITextIndexPrefixes> selector) =>
+			Assign(a => a.IndexPrefixes = selector?.Invoke(new TextIndexPrefixesDescriptor()));
 		public TextPropertyDescriptor<T> Index(bool? index = true) => Assign(a => a.Index = index);
 		public TextPropertyDescriptor<T> IndexOptions(IndexOptions? indexOptions) => Assign(a => a.IndexOptions = indexOptions);
 		public TextPropertyDescriptor<T> Norms(bool? enabled = true) => Assign(a => a.Norms = enabled);

src/Tests/Tests.Configuration/tests.default.yaml

@@ -5,7 +5,7 @@
 # tracked by git).
 
 # mode either u (unit test), i (integration test) or m (mixed mode)
-mode: i
+mode: u
 # the elasticsearch version that should be started
 # Can be a snapshot version of sonatype or "latest" to get the latest snapshot of sonatype
 elasticsearch_version: 6.3.0

src/Tests/Tests/Mapping/Types/Core/Text/TextPropertyTests.cs

@@ -31,6 +31,11 @@ public TextPropertyTests(WritableCluster cluster, EndpointUsage usage) : base(cl
 						max = 100.00,
 						min_segment_size = 2
 					},
+					index_prefixes = new
+					{
+						min_chars = 1,
+						max_chars = 10
+					},
 					fields = new
 					{
 						raw = new
@@ -68,6 +73,10 @@ public TextPropertyTests(WritableCluster cluster, EndpointUsage usage) : base(cl
 						.Max(100)
 						.MinSegmentSize(2)
 					)
+					.IndexPrefixes(i => i
+						.MinCharacters(1)
+						.MaxCharacters(10)
+					)
 					.Fields(fd => fd
 						.Keyword(k => k
 							.Name("raw")
@@ -101,6 +110,11 @@ public TextPropertyTests(WritableCluster cluster, EndpointUsage usage) : base(cl
 						Max = 100,
 						MinSegmentSize = 2
 					},
+					IndexPrefixes = new TextIndexPrefixes
+					{
+						MinCharacters = 1,
+						MaxCharacters = 10
+					},
 					Fields = new Properties
 					{
 						{ "raw", new KeywordProperty