Deprecation check for percolator.map_unmapped_fields_as_string (#36460)

Adds a deprecation check for the removed setting
`index.percolator.map_unmapped_fields_as_string`

Author: gwbrown

x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/DeprecationChecks.java

@@ -49,6 +49,7 @@ private DeprecationChecks() {
         Collections.unmodifiableList(Arrays.asList(
             IndexDeprecationChecks::oldIndicesCheck,
             IndexDeprecationChecks::delimitedPayloadFilterCheck,
+            IndexDeprecationChecks::percolatorUnmappedFieldsAsStringCheck,
             IndexDeprecationChecks::indexNameCheck
             ));
 

x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/IndexDeprecationChecks.java

@@ -116,4 +116,17 @@ static DeprecationIssue indexNameCheck(IndexMetaData indexMetaData) {
         }
         return null;
     }
+
+    static DeprecationIssue percolatorUnmappedFieldsAsStringCheck(IndexMetaData indexMetaData) {
+        if (indexMetaData.getSettings().hasValue("index.percolator.map_unmapped_fields_as_text")) {
+            String settingValue = indexMetaData.getSettings().get("index.percolator.map_unmapped_fields_as_text");
+            return new DeprecationIssue(DeprecationIssue.Level.WARNING,
+                "Setting index.percolator.map_unmapped_fields_as_text has been renamed",
+                "https://www.elastic.co/guide/en/elasticsearch/reference/master/breaking-changes-7.0.html" +
+                    "#_percolator",
+                "The index setting [index.percolator.map_unmapped_fields_as_text] currently set to [" + settingValue +
+                    "] been removed in favor of [index.percolator.map_unmapped_fields_as_text].");
+        }
+        return null;
+    }
 }

x-pack/plugin/deprecation/src/test/java/org/elasticsearch/xpack/deprecation/IndexDeprecationChecksTests.java

@@ -14,6 +14,7 @@
 import org.elasticsearch.xpack.core.deprecation.DeprecationIssue;
 
 import java.util.List;
+import java.util.Locale;
 
 import static java.util.Collections.singletonList;
 import static org.elasticsearch.xpack.deprecation.DeprecationChecks.INDEX_SETTINGS_CHECKS;
@@ -76,4 +77,33 @@ public void testIndexNameCheck(){
         List<DeprecationIssue> noIssues = DeprecationChecks.filterChecks(INDEX_SETTINGS_CHECKS, c -> c.apply(goodIndex));
         assertTrue(noIssues.isEmpty());
     }
+
+    public void testPercolatorUnmappedFieldsAsStringCheck() {
+        boolean settingValue = randomBoolean();
+        Settings settings = settings(
+            VersionUtils.randomVersionBetween(random(), Version.V_6_0_0, VersionUtils.getPreviousVersion(Version.CURRENT)))
+            .put("index.percolator.map_unmapped_fields_as_text", settingValue).build();
+        final IndexMetaData badIndex = IndexMetaData.builder(randomAlphaOfLengthBetween(1,30).toLowerCase(Locale.ROOT))
+            .settings(settings)
+            .numberOfShards(randomIntBetween(1,100))
+            .numberOfReplicas(randomIntBetween(1,15))
+            .build();
+
+        DeprecationIssue expected = new DeprecationIssue(DeprecationIssue.Level.WARNING,
+            "Setting index.percolator.map_unmapped_fields_as_text has been renamed",
+            "https://www.elastic.co/guide/en/elasticsearch/reference/master/breaking-changes-7.0.html" +
+                "#_percolator",
+            "The index setting [index.percolator.map_unmapped_fields_as_text] currently set to [" + settingValue +
+                "] been removed in favor of [index.percolator.map_unmapped_fields_as_text].");
+        List<DeprecationIssue> issues = DeprecationChecks.filterChecks(INDEX_SETTINGS_CHECKS, c -> c.apply(badIndex));
+        assertEquals(singletonList(expected), issues);
+
+        final IndexMetaData goodIndex = IndexMetaData.builder(randomAlphaOfLengthBetween(1,30).toLowerCase(Locale.ROOT))
+            .settings(settings(Version.CURRENT))
+            .numberOfShards(randomIntBetween(1,100))
+            .numberOfReplicas(randomIntBetween(1,15))
+            .build();
+        List<DeprecationIssue> noIssues = DeprecationChecks.filterChecks(INDEX_SETTINGS_CHECKS, c -> c.apply(goodIndex));
+        assertTrue(noIssues.isEmpty());
+    }
 }