Remove `nGram` and `edgeNGram` token filter names (#38911)

In #30209 we deprecated the camel case `nGram` filter name in favour of `ngram` and
did the same for `edgeNGram` and `edge_ngram`. Using these names has been deprecated
since 6.4 and is issuing deprecation warnings since then.
I think we can remove these filters in 8.0. In a backport of this PR I would change what was a
dreprecation warning from 6.4. to an error starting with new indices created in 7.0.

docs/reference/analysis/tokenfilters/edgengram-tokenfilter.asciidoc

@@ -1,9 +1,9 @@
 [[analysis-edgengram-tokenfilter]]
 === Edge NGram Token Filter
 
-A token filter of type `edgeNGram`.
+A token filter of type `edge_ngram`.
 
-The following are settings that can be set for a `edgeNGram` token
+The following are settings that can be set for a `edge_ngram` token
 filter type:
 
 [cols="<,<",options="header",]

docs/reference/analysis/tokenfilters/ngram-tokenfilter.asciidoc

@@ -1,9 +1,9 @@
 [[analysis-ngram-tokenfilter]]
 === NGram Token Filter
 
-A token filter of type `nGram`.
+A token filter of type `ngram`.
 
-The following are settings that can be set for a `nGram` token filter
+The following are settings that can be set for a `ngram` token filter
 type:
 
 [cols="<,<",options="header",]

docs/reference/migration/migrate_8_0.asciidoc

@@ -9,4 +9,8 @@ your application to {es} 8.0.
 
 See also <<release-highlights>> and <<es-release-notes>>.
 
-coming[8.0.0]
+coming[8.0.0]
+
+* <<breaking_80_mappings_changes>>
+
+include::migrate_8_0/mappings.asciidoc[]

docs/reference/migration/migrate_8_0/mappings.asciidoc

@@ -0,0 +1,10 @@
+[float]
+[[breaking_80_mappings_changes]]
+=== Mapping changes
+
+[float]
+==== The `nGram` and `edgeNGram` token filter names have been removed
+
+The `nGram` and `edgeNGram` token filter names that have been deprecated since
+version 6.4 have been removed. Both token filters should be used by their 
+alternative names `ngram` and `edge_ngram` instead.

modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/CommonAnalysisPlugin.java

@@ -414,14 +414,6 @@ public class CommonAnalysisPlugin extends Plugin implements AnalysisPlugin, Scri
         filters.add(PreConfiguredTokenFilter.singleton("dutch_stem", false, input -> new SnowballFilter(input, new DutchStemmer())));
         filters.add(PreConfiguredTokenFilter.singleton("edge_ngram", false, false, input ->
                 new EdgeNGramTokenFilter(input, 1)));
-        filters.add(PreConfiguredTokenFilter.singletonWithVersion("edgeNGram", false, false, (reader, version) -> {
-            if (version.onOrAfter(org.elasticsearch.Version.V_6_4_0)) {
-                deprecationLogger.deprecatedAndMaybeLog("edgeNGram_deprecation",
-                        "The [edgeNGram] token filter name is deprecated and will be removed in a future version. "
-                                + "Please change the filter name to [edge_ngram] instead.");
-            }
-            return new EdgeNGramTokenFilter(reader, 1);
-            }));
         filters.add(PreConfiguredTokenFilter.singleton("elision", true,
                 input -> new ElisionFilter(input, FrenchAnalyzer.DEFAULT_ARTICLES)));
         filters.add(PreConfiguredTokenFilter.singleton("french_stem", false, input -> new SnowballFilter(input, new FrenchStemmer())));
@@ -438,14 +430,6 @@ public class CommonAnalysisPlugin extends Plugin implements AnalysisPlugin, Scri
                         LimitTokenCountFilterFactory.DEFAULT_MAX_TOKEN_COUNT,
                         LimitTokenCountFilterFactory.DEFAULT_CONSUME_ALL_TOKENS)));
         filters.add(PreConfiguredTokenFilter.singleton("ngram", false, false, reader -> new NGramTokenFilter(reader, 1, 2, false)));
-        filters.add(PreConfiguredTokenFilter.singletonWithVersion("nGram", false, false, (reader, version) -> {
-            if (version.onOrAfter(org.elasticsearch.Version.V_6_4_0)) {
-                deprecationLogger.deprecatedAndMaybeLog("nGram_deprecation",
-                        "The [nGram] token filter name is deprecated and will be removed in a future version. "
-                                + "Please change the filter name to [ngram] instead.");
-            }
-            return new NGramTokenFilter(reader, 1, 2, false);
-        }));
         filters.add(PreConfiguredTokenFilter.singleton("persian_normalization", true, PersianNormalizationFilter::new));
         filters.add(PreConfiguredTokenFilter.singleton("porter_stem", false, PorterStemFilter::new));
         filters.add(PreConfiguredTokenFilter.singleton("reverse", false, ReverseStringFilter::new));

modules/analysis-common/src/test/java/org/elasticsearch/analysis/common/CommonAnalysisFactoryTests.java

@@ -185,7 +185,6 @@ public class CommonAnalysisFactoryTests extends AnalysisFactoryTestCase {
         filters.put("delimited_payload", org.apache.lucene.analysis.payloads.DelimitedPayloadTokenFilterFactory.class);
         filters.put("dutch_stem", SnowballPorterFilterFactory.class);
         filters.put("edge_ngram", null);
-        filters.put("edgeNGram", null);
         filters.put("elision", null);
         filters.put("french_stem", SnowballPorterFilterFactory.class);
         filters.put("german_stem", null);
@@ -197,7 +196,6 @@ public class CommonAnalysisFactoryTests extends AnalysisFactoryTestCase {
         filters.put("length", null);
         filters.put("limit", LimitTokenCountFilterFactory.class);
         filters.put("ngram", null);
-        filters.put("nGram", null);
         filters.put("persian_normalization", null);
         filters.put("porter_stem", null);
         filters.put("reverse", ReverseStringFilterFactory.class);

modules/analysis-common/src/test/java/org/elasticsearch/analysis/common/CommonAnalysisPluginTests.java

@@ -20,8 +20,6 @@
 package org.elasticsearch.analysis.common;
 
 import org.apache.lucene.analysis.Analyzer;
-import org.apache.lucene.analysis.MockTokenizer;
-import org.apache.lucene.analysis.Tokenizer;
 import org.elasticsearch.Version;
 import org.elasticsearch.cluster.metadata.IndexMetaData;
 import org.elasticsearch.common.settings.Settings;
@@ -29,98 +27,14 @@ import org.elasticsearch.env.Environment;
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.analysis.IndexAnalyzers;
 import org.elasticsearch.index.analysis.NamedAnalyzer;
-import org.elasticsearch.index.analysis.TokenFilterFactory;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.test.IndexSettingsModule;
 import org.elasticsearch.test.VersionUtils;
 
 import java.io.IOException;
-import java.io.StringReader;
-import java.util.Map;
 
 public class CommonAnalysisPluginTests extends ESTestCase {
 
-    /**
-     * Check that the deprecated name "nGram" issues a deprecation warning for indices created since 6.3.0
-     */
-    public void testNGramDeprecationWarning() throws IOException {
-        Settings settings = Settings.builder().put(Environment.PATH_HOME_SETTING.getKey(), createTempDir())
-                .put(IndexMetaData.SETTING_VERSION_CREATED, VersionUtils.randomVersionBetween(random(), Version.V_6_4_0, Version.CURRENT))
-                .build();
-
-        IndexSettings idxSettings = IndexSettingsModule.newIndexSettings("index", settings);
-        try (CommonAnalysisPlugin commonAnalysisPlugin = new CommonAnalysisPlugin()) {
-            Map<String, TokenFilterFactory> tokenFilters = createTestAnalysis(idxSettings, settings, commonAnalysisPlugin).tokenFilter;
-            TokenFilterFactory tokenFilterFactory = tokenFilters.get("nGram");
-            Tokenizer tokenizer = new MockTokenizer();
-            tokenizer.setReader(new StringReader("foo bar"));
-            assertNotNull(tokenFilterFactory.create(tokenizer));
-            assertWarnings(
-                    "The [nGram] token filter name is deprecated and will be removed in a future version. "
-                    + "Please change the filter name to [ngram] instead.");
-        }
-    }
-
-    /**
-     * Check that the deprecated name "nGram" does NOT issues a deprecation warning for indices created before 6.4.0
-     */
-    public void testNGramNoDeprecationWarningPre6_4() throws IOException {
-        Settings settings = Settings.builder().put(Environment.PATH_HOME_SETTING.getKey(), createTempDir())
-                .put(IndexMetaData.SETTING_VERSION_CREATED,
-                        VersionUtils.randomVersionBetween(random(), Version.V_6_0_0, Version.V_6_3_0))
-                .build();
-
-        IndexSettings idxSettings = IndexSettingsModule.newIndexSettings("index", settings);
-        try (CommonAnalysisPlugin commonAnalysisPlugin = new CommonAnalysisPlugin()) {
-            Map<String, TokenFilterFactory> tokenFilters = createTestAnalysis(idxSettings, settings, commonAnalysisPlugin).tokenFilter;
-            TokenFilterFactory tokenFilterFactory = tokenFilters.get("nGram");
-            Tokenizer tokenizer = new MockTokenizer();
-            tokenizer.setReader(new StringReader("foo bar"));
-            assertNotNull(tokenFilterFactory.create(tokenizer));
-        }
-    }
-
-    /**
-     * Check that the deprecated name "edgeNGram" issues a deprecation warning for indices created since 6.3.0
-     */
-    public void testEdgeNGramDeprecationWarning() throws IOException {
-        Settings settings = Settings.builder().put(Environment.PATH_HOME_SETTING.getKey(), createTempDir())
-                .put(IndexMetaData.SETTING_VERSION_CREATED, VersionUtils.randomVersionBetween(random(), Version.V_6_4_0, Version.CURRENT))
-                .build();
-
-        IndexSettings idxSettings = IndexSettingsModule.newIndexSettings("index", settings);
-        try (CommonAnalysisPlugin commonAnalysisPlugin = new CommonAnalysisPlugin()) {
-            Map<String, TokenFilterFactory> tokenFilters = createTestAnalysis(idxSettings, settings, commonAnalysisPlugin).tokenFilter;
-            TokenFilterFactory tokenFilterFactory = tokenFilters.get("edgeNGram");
-            Tokenizer tokenizer = new MockTokenizer();
-            tokenizer.setReader(new StringReader("foo bar"));
-            assertNotNull(tokenFilterFactory.create(tokenizer));
-            assertWarnings(
-                    "The [edgeNGram] token filter name is deprecated and will be removed in a future version. "
-                    + "Please change the filter name to [edge_ngram] instead.");
-        }
-    }
-
-    /**
-     * Check that the deprecated name "edgeNGram" does NOT issues a deprecation warning for indices created before 6.4.0
-     */
-    public void testEdgeNGramNoDeprecationWarningPre6_4() throws IOException {
-        Settings settings = Settings.builder().put(Environment.PATH_HOME_SETTING.getKey(), createTempDir())
-                .put(IndexMetaData.SETTING_VERSION_CREATED,
-                        VersionUtils.randomVersionBetween(random(), Version.V_6_0_0, Version.V_6_3_0))
-                .build();
-
-        IndexSettings idxSettings = IndexSettingsModule.newIndexSettings("index", settings);
-        try (CommonAnalysisPlugin commonAnalysisPlugin = new CommonAnalysisPlugin()) {
-            Map<String, TokenFilterFactory> tokenFilters = createTestAnalysis(idxSettings, settings, commonAnalysisPlugin).tokenFilter;
-            TokenFilterFactory tokenFilterFactory = tokenFilters.get("edgeNGram");
-            Tokenizer tokenizer = new MockTokenizer();
-            tokenizer.setReader(new StringReader("foo bar"));
-            assertNotNull(tokenFilterFactory.create(tokenizer));
-        }
-    }
-
-
     /**
      * Check that the deprecated analyzer name "standard_html_strip" throws exception for indices created since 7.0.0
      */

modules/analysis-common/src/test/java/org/elasticsearch/analysis/common/HighlighterWithAnalyzersTests.java

@@ -81,7 +81,7 @@ public class HighlighterWithAnalyzersTests extends ESIntegTestCase {
                         .put("analysis.tokenizer.autocomplete.max_gram", 20)
                         .put("analysis.tokenizer.autocomplete.min_gram", 1)
                         .put("analysis.tokenizer.autocomplete.token_chars", "letter,digit")
-                        .put("analysis.tokenizer.autocomplete.type", "nGram")
+                        .put("analysis.tokenizer.autocomplete.type", "ngram")
                         .put("analysis.filter.wordDelimiter.type", "word_delimiter")
                         .putList("analysis.filter.wordDelimiter.type_table",
                                 "& => ALPHANUM", "| => ALPHANUM", "! => ALPHANUM",

modules/analysis-common/src/test/resources/rest-api-spec/test/analysis-common/30_tokenizers.yml

@@ -23,38 +23,6 @@
     - match:  { detail.tokenizer.tokens.0.token: Foo Bar! }
 
 ---
-"nGram":
-    - do:
-        indices.analyze:
-          body:
-            text: good
-            explain: true
-            tokenizer:
-              type: nGram
-              min_gram: 2
-              max_gram: 2
-    - length: { detail.tokenizer.tokens: 3 }
-    - match:  { detail.tokenizer.name: _anonymous_tokenizer }
-    - match:  { detail.tokenizer.tokens.0.token: go }
-    - match:  { detail.tokenizer.tokens.1.token: oo }
-    - match:  { detail.tokenizer.tokens.2.token: od }
-
----
-"nGram_exception":
-    - skip:
-        version: " - 6.99.99"
-        reason: only starting from version 7.x this throws an error
-    - do:
-        catch: /The difference between max_gram and min_gram in NGram Tokenizer must be less than or equal to[:] \[1\] but was \[2\]\. This limit can be set by changing the \[index.max_ngram_diff\] index level setting\./
-        indices.analyze:
-          body:
-            text: good
-            explain: true
-            tokenizer:
-              type: nGram
-              min_gram: 2
-              max_gram: 4
----
 "simple_pattern":
     - do:
         indices.analyze:
@@ -133,7 +101,7 @@
             text: "foobar"
             explain: true
             tokenizer:
-              type: nGram
+              type: ngram
               min_gram: 3
               max_gram: 3
     - length: { detail.tokenizer.tokens: 4 }
@@ -162,15 +130,31 @@
           body:
             text: "foo"
             explain: true
-            tokenizer: nGram
+            tokenizer: ngram
     - length: { detail.tokenizer.tokens: 5 }
-    - match:  { detail.tokenizer.name: nGram }
+    - match:  { detail.tokenizer.name: ngram }
     - match:  { detail.tokenizer.tokens.0.token: f }
     - match:  { detail.tokenizer.tokens.1.token: fo }
     - match:  { detail.tokenizer.tokens.2.token: o }
     - match:  { detail.tokenizer.tokens.3.token: oo }
     - match:  { detail.tokenizer.tokens.4.token: o }
 
+---
+"ngram_exception":
+    - skip:
+        version: " - 6.99.99"
+        reason: only starting from version 7.x this throws an error
+    - do:
+        catch: /The difference between max_gram and min_gram in NGram Tokenizer must be less than or equal to[:] \[1\] but was \[2\]\. This limit can be set by changing the \[index.max_ngram_diff\] index level setting\./
+        indices.analyze:
+          body:
+            text: good
+            explain: true
+            tokenizer:
+              type: ngram
+              min_gram: 2
+              max_gram: 4
+
 ---
 "edge_ngram":
     - do:
@@ -194,7 +178,7 @@
             text: "foo"
             explain: true
             tokenizer:
-              type: edgeNGram
+              type: edge_ngram
               min_gram: 1
               max_gram: 3
     - length: { detail.tokenizer.tokens: 3 }
@@ -219,9 +203,9 @@
           body:
             text: "foo"
             explain: true
-            tokenizer: edgeNGram
+            tokenizer: edge_ngram
     - length: { detail.tokenizer.tokens: 2 }
-    - match:  { detail.tokenizer.name: edgeNGram }
+    - match:  { detail.tokenizer.name: edge_ngram }
     - match:  { detail.tokenizer.tokens.0.token: f }
     - match:  { detail.tokenizer.tokens.1.token: fo }
 

modules/analysis-common/src/test/resources/rest-api-spec/test/indices.analyze/10_analyze.yml

@@ -76,7 +76,7 @@
                 analysis:
                   tokenizer:
                     trigram:
-                      type: nGram
+                      type: ngram
                       min_gram: 3
                       max_gram: 3
                   filter: