Fix standard filter BWC check to allow for cacheing bug (#62649)

The `standard` tokenfilter was removed by #33310, and should have been
unuseable in any indexes created since 7.0. However, a cacheing bug fixed
by #51092 meant that it was still possible in certain circumstances to create
indexes referencing the standard filter in versions up to 7.5.2. Our checks
in AnalysisModule still refer to 7.0.0, however, meaning that a cluster that
contains one of these rogue indexes cannot be upgraded.

This commit adjusts the AnalysisModule checks so that we only refuse to
build a mapping referring to standard filter if the index created version is
7.6 or later.

Fixes #62644

Author: romseygeek

server/src/main/java/org/elasticsearch/indices/analysis/AnalysisModule.java

@@ -183,7 +183,10 @@ static Map<String, PreConfiguredTokenFilter> setupPreConfiguredTokenFilters(List
         // Add "standard" for old indices (bwc)
         preConfiguredTokenFilters.register( "standard",
             PreConfiguredTokenFilter.elasticsearchVersion("standard", true, (reader, version) -> {
-                if (version.before(Version.V_7_0_0)) {
+                // This was originally removed in 7_0_0 but due to a cacheing bug it was still possible
+                // in certain circumstances to create a new index referencing the standard token filter
+                // until version 7_5_2
+                if (version.before(Version.V_7_6_0)) {
                     deprecationLogger.deprecatedAndMaybeLog("standard_deprecation",
                         "The [standard] token filter is deprecated and will be removed in a future version.");
                 } else {

server/src/test/java/org/elasticsearch/indices/analysis/AnalysisModuleTests.java

@@ -228,28 +228,27 @@ public void testUnderscoreInAnalyzerName() throws IOException {
     }
 
     public void testStandardFilterBWC() throws IOException {
-        Version version = VersionUtils.randomVersionBetween(random(), Version.V_6_0_0, Version.CURRENT.minimumCompatibilityVersion());
-        // bwc deprecation
+        // standard tokenfilter should have been removed entirely in the 7x line.  However, a
+        // cacheing bug meant that it was still possible to create indexes using a standard
+        // filter until 7.6
         {
+            Version version = VersionUtils.randomVersionBetween(random(), Version.V_7_6_0, Version.CURRENT);
             final Settings settings = Settings.builder().put("index.analysis.analyzer.my_standard.tokenizer", "standard")
                 .put("index.analysis.analyzer.my_standard.filter", "standard")
                 .put(Environment.PATH_HOME_SETTING.getKey(), createTempDir().toString())
                 .put(IndexMetadata.SETTING_VERSION_CREATED, version)
                 .build();
-            IndexAnalyzers analyzers = getIndexAnalyzers(settings);
-            assertTokenStreamContents(analyzers.get("my_standard").tokenStream("", "test"), new String[]{"test"});
-            assertWarnings("The [standard] token filter is deprecated and will be removed in a future version.");
+            IllegalArgumentException exc = expectThrows(IllegalArgumentException.class, () -> getIndexAnalyzers(settings));
+            assertThat(exc.getMessage(), equalTo("The [standard] token filter has been removed."));
         }
-        // removal
         {
-            final Settings settings = Settings.builder()
-                .put("index.analysis.analyzer.my_standard.tokenizer", "standard")
+            Version version = VersionUtils.randomVersionBetween(random(), Version.V_7_0_0, Version.V_7_5_2);
+            final Settings settings = Settings.builder().put("index.analysis.analyzer.my_standard.tokenizer", "standard")
                 .put("index.analysis.analyzer.my_standard.filter", "standard")
-                .put(Environment.PATH_HOME_SETTING.getKey(), createTempDir().toString())
-                .put(IndexMetadata.SETTING_VERSION_CREATED, Version.V_7_0_0)
+                .put(Environment.PATH_HOME_SETTING.getKey(), createTempDir().toString()).put(IndexMetadata.SETTING_VERSION_CREATED, version)
                 .build();
-            IllegalArgumentException exc = expectThrows(IllegalArgumentException.class, () -> getIndexAnalyzers(settings));
-            assertThat(exc.getMessage(), equalTo("The [standard] token filter has been removed."));
+            getIndexAnalyzers(settings);
+            assertWarnings("The [standard] token filter is deprecated and will be removed in a future version.");
         }
     }