deprecate standard token filter as per elastic/elasticsearch#33468

src/Nest/Analysis/TokenFilters/StandardTokenFilter.cs

@@ -1,17 +1,22 @@
-namespace Nest
+using System;
+
+namespace Nest
 {
 	/// <summary>
 	/// A token filter of type standard that normalizes tokens extracted with the Standard Tokenizer.
 	/// </summary>
+	[Obsolete(" The `standard` token filter has been deprecated because it doesn't change anything in the stream. It will be removed in 7.0.")]
 	public interface IStandardTokenFilter : ITokenFilter { }
 
 	/// <inheritdoc />
+	[Obsolete(" The `standard` token filter has been deprecated because it doesn't change anything in the stream. It will be removed in 7.0.")]
 	public class StandardTokenFilter : TokenFilterBase, IStandardTokenFilter
 	{
 		public StandardTokenFilter() : base("standard") { }
 	}
 
 	/// <inheritdoc />
+	[Obsolete(" The `standard` token filter has been deprecated because it doesn't change anything in the stream. It will be removed in 7.0.")]
 	public class StandardTokenFilterDescriptor
 		: TokenFilterDescriptorBase<StandardTokenFilterDescriptor, IStandardTokenFilter>, IStandardTokenFilter
 	{

src/Nest/Analysis/TokenFilters/TokenFilterJsonConverter.cs

@@ -47,7 +47,9 @@ public override object ReadJson(JsonReader reader, Type objectType, object exist
 				case "stemmer": return o.ToObject<StemmerTokenFilter>(ElasticContractResolver.Empty);
 				case "stemmer_override": return o.ToObject<StemmerOverrideTokenFilter>(ElasticContractResolver.Empty);
 				case "stop": return o.ToObject<StopTokenFilter>(ElasticContractResolver.Empty);
+#pragma warning disable 618
 				case "standard": return o.ToObject<StandardTokenFilter>(ElasticContractResolver.Empty);
+#pragma warning restore 618
 				case "synonym": return o.ToObject<SynonymTokenFilter>(ElasticContractResolver.Empty);
 				case "synonym_graph": return o.ToObject<SynonymGraphTokenFilter>(ElasticContractResolver.Empty);
 				case "trim": return o.ToObject<TrimTokenFilter>(ElasticContractResolver.Empty);

src/Nest/Analysis/TokenFilters/TokenFilters.cs

@@ -214,8 +214,10 @@ public TokenFiltersDescriptor Snowball(string name, Func<SnowballTokenFilterDesc
 		/// <summary>
 		/// A token filter of type standard that normalizes tokens extracted with the Standard Tokenizer.
 		/// </summary>
+#pragma warning disable 618
 		public TokenFiltersDescriptor Standard(string name, Func<StandardTokenFilterDescriptor, IStandardTokenFilter> selector = null) =>
 			Assign(name, selector.InvokeOrDefault(new StandardTokenFilterDescriptor()));
+#pragma warning restore 618
 
 		/// <summary>
 		/// A filter that stems words (similar to snowball, but with more options).

src/Nest/Indices/Analyze/AnalyzeTokenFilters.cs

@@ -236,8 +236,10 @@ public AnalyzeTokenFiltersDescriptor Snowball(Func<SnowballTokenFilterDescriptor
 		/// <summary>
 		/// A token filter of type standard that normalizes tokens extracted with the Standard Tokenizer.
 		/// </summary>
+#pragma warning disable 618
 		public AnalyzeTokenFiltersDescriptor Standard(Func<StandardTokenFilterDescriptor, IStandardTokenFilter> selector = null) =>
 			AssignIfNotNull(selector.InvokeOrDefault(new StandardTokenFilterDescriptor()));
+#pragma warning restore 618
 
 		/// <summary>
 		/// A filter that stems words (similar to snowball, but with more options).

src/Tests/Tests/Analysis/TokenFilters/TokenFilterTests.cs

@@ -561,7 +561,9 @@ public class StandardTests : TokenFilterAssertionBase<StandardTests>
 		{
 			public override FuncTokenFilters Fluent => (n, tf) => tf.Standard(n);
 
+#pragma warning disable 618
 			public override ITokenFilter Initializer => new StandardTokenFilter();
+#pragma warning restore 618
 
 			public override object Json => new { type = "standard" };
 			public override string Name => "standard";