Support single or array of char filters and token filters (#3294)

Closes #3262

(cherry picked from commit 576882a)

Author: russcam

src/Nest/Analysis/Analyzers/CustomAnalyzer.cs

@@ -15,12 +15,14 @@ public interface ICustomAnalyzer : IAnalyzer
 		/// The logical / registered name of the tokenizer to use.
 		/// </summary>
 		[JsonProperty("char_filter")]
+		[JsonConverter(typeof(ReadSingleOrEnumerableJsonConverter<string>))]
 		IEnumerable<string> CharFilter { get; set; }
 
 		/// <summary>
 		/// An optional list of logical / registered name of token filters.
 		/// </summary>
 		[JsonProperty("filter")]
+		[JsonConverter(typeof(ReadSingleOrEnumerableJsonConverter<string>))]
 		IEnumerable<string> Filter { get; set; }
 
 		/// <summary>

src/Nest/Analysis/Normalizers/CustomNormalizer.cs

@@ -17,12 +17,14 @@ public interface ICustomNormalizer : INormalizer
 		/// Char filters to normalize the keyword
 		/// </summary>
 		[JsonProperty("char_filter")]
+		[JsonConverter(typeof(ReadSingleOrEnumerableJsonConverter<string>))]
 		IEnumerable<string> CharFilter { get; set; }
 
 		/// <summary>
 		/// An optional list of logical / registered name of token filters.
 		/// </summary>
 		[JsonProperty("filter")]
+		[JsonConverter(typeof(ReadSingleOrEnumerableJsonConverter<string>))]
 		IEnumerable<string> Filter { get; set; }
 	}
 

src/Nest/CommonAbstractions/SerializationBehavior/GenericJsonConverters/ReadSingleOrEnumerableJsonConverter.cs

@@ -16,9 +16,7 @@ public override object ReadJson(JsonReader reader, Type objectType, object exist
 
 		public override bool CanWrite => false;
 
-		public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
-		{
+		public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer) =>
 			throw new NotSupportedException();
-		}
 	}
 }

src/Tests/Reproduce/GithubIssue3262.cs

@@ -0,0 +1,79 @@
+using System;
+using System.Text;
+using Elastic.Xunit.XunitPlumbing;
+using Elasticsearch.Net;
+using FluentAssertions;
+using Nest;
+using Tests.Framework;
+using Tests.Framework.ManagedElasticsearch.Clusters;
+
+namespace Tests.Reproduce
+{
+	public class GithubIssue3262
+	{
+		[U]
+		public void CanDeserializeSingleFilterAndCharacterFilter()
+		{
+			var json = @"{
+			  ""products_purchasing"": {
+				""settings"": {
+				  ""index"": {
+					""number_of_shards"": ""5"",
+					""provided_name"": ""products_purchasing"",
+					""creation_date"": ""1510930394462"",
+					""analysis"": {
+					  ""normalizer"": {
+						""lowercase"": {
+						  ""filter"": ""lowercase"",
+						  ""type"": ""custom"",
+						  ""char_filter"": ""words""
+						}
+					  },
+					  ""analyzer"": {
+						""whitespace_lowercase"": {
+						  ""filter"": ""lowercase"",
+						  ""type"": ""custom"",
+						  ""tokenizer"": ""whitespace""
+						},
+						""keyword_lowercase"": {
+						  ""filter"": ""lowercase"",
+						  ""type"": ""custom"",
+						  ""tokenizer"": ""keyword""
+						}
+					  },
+					  ""char_filter"": {
+						""words"": {
+						  ""pattern"": ""[(^([^A-Za-z\\s]*\\s)*|[^A-Za-z\\s])]"",
+						  ""type"": ""pattern_replace"",
+						  ""replacement"": """"
+						}
+					  }
+					},
+					""number_of_replicas"": ""1"",
+					""uuid"": ""peH2yqVLTIOc4ScTUYTtEA"",
+					""version"": {
+					  ""created"": ""5050099""
+					}
+				  }
+				}
+			  }
+			}";
+
+			var bytes = Encoding.UTF8.GetBytes(json);
+
+			var pool = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));
+			var connectionSettings = new ConnectionSettings(pool, new InMemoryConnection(bytes));
+			var client = new ElasticClient(connectionSettings);
+
+			Action getIndexRequest = () => client.GetIndex(new GetIndexRequest("products_purchasing"));
+
+			getIndexRequest.ShouldNotThrow();
+
+			var response = client.GetIndex(new GetIndexRequest("products_purchasing"));
+
+			var normalizer = response.Indices["products_purchasing"].Settings.Analysis.Normalizers["lowercase"] as ICustomNormalizer;
+			normalizer.Should().NotBeNull();
+			normalizer.Filter.Should().NotBeNull().And.HaveCount(1);
+		}
+	}
+}