[Rest Api Compatibility] Indicies boost in object format

Previouslly removed elastic#55078 indices_boost field is available when used
with rest api compatibility

relates elastic#51816

Author: pgomulka

rest-api-spec/build.gradle

@@ -105,7 +105,6 @@ tasks.named("yamlRestCompatTest").configure {
     'mtermvectors/21_deprecated_with_types/Deprecated camel case and _ parameters should fail in Term Vectors query',
     'mtermvectors/30_mix_typeless_typeful/mtermvectors without types on an index that has types',
     'search/10_source_filtering/docvalue_fields with default format', //use_field_mapping change
-    'search/40_indices_boost/Indices boost using object', //indices_boost
     'search/150_rewrite_on_coordinator/Ensure that we fetch the document only once', //terms_lookup
     'search/171_terms_query_with_types/Terms Query with No.of terms exceeding index.max_terms_count should FAIL', //bulk
     'search/260_parameter_validation/test size=-1 is deprecated', //size=-1 change

server/src/main/java/org/elasticsearch/search/builder/SearchSourceBuilder.java

@@ -10,6 +10,7 @@
 
 import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.Version;
+import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.core.Booleans;
 import org.elasticsearch.core.Nullable;
 import org.elasticsearch.common.xcontent.ParseField;
@@ -18,6 +19,7 @@
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
+import org.elasticsearch.core.RestApiVersion;
 import org.elasticsearch.core.TimeValue;
 import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.ToXContentObject;
@@ -68,6 +70,8 @@
  * @see org.elasticsearch.action.search.SearchRequest#source(SearchSourceBuilder)
  */
 public final class SearchSourceBuilder implements Writeable, ToXContentObject, Rewriteable<SearchSourceBuilder> {
+    private static final DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(SearchSourceBuilder.class);
+
     public static final ParseField FROM_FIELD = new ParseField("from");
     public static final ParseField SIZE_FIELD = new ParseField("size");
     public static final ParseField TIMEOUT_FIELD = new ParseField("timeout");
@@ -1164,6 +1168,20 @@ public void parseXContent(XContentParser parser, boolean checkTrailingTokens) th
                     while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
                         scriptFields.add(new ScriptField(parser));
                     }
+                } else if (parser.getRestApiVersion() == RestApiVersion.V_7 &&
+                    INDICES_BOOST_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
+                    deprecationLogger.compatibleApiWarning("indices_boost_object_format",
+                        "Object format in indices_boost is deprecated, please use array format instead");
+                    while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
+                        if (token == XContentParser.Token.FIELD_NAME) {
+                            currentFieldName = parser.currentName();
+                        } else if (token.isValue()) {
+                            indexBoosts.add(new IndexBoost(currentFieldName, parser.floatValue()));
+                        } else {
+                            throw new ParsingException(parser.getTokenLocation(), "Unknown key for a " + token +
+                                " in [" + currentFieldName + "].", parser.getTokenLocation());
+                        }
+                    }
                 } else if (AGGREGATIONS_FIELD.match(currentFieldName, parser.getDeprecationHandler())
                         || AGGS_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                     aggregations = AggregatorFactories.parseAggregators(parser);

server/src/test/java/org/elasticsearch/search/builder/SearchSourceBuilderTests.java

@@ -400,6 +400,17 @@ public void testToXContentWithPointInTime() throws IOException {
     }
 
     public void testParseIndicesBoost() throws IOException {
+        {
+            String restContent = " { \"indices_boost\": {\"foo\": 1.0, \"bar\": 2.0}}";
+            try (XContentParser parser = createParser(JsonXContent.jsonXContent, restContent)) {
+                SearchSourceBuilder searchSourceBuilder = SearchSourceBuilder.fromXContent(parser);
+                assertEquals(2, searchSourceBuilder.indexBoosts().size());
+                assertEquals(new SearchSourceBuilder.IndexBoost("foo", 1.0f), searchSourceBuilder.indexBoosts().get(0));
+                assertEquals(new SearchSourceBuilder.IndexBoost("bar", 2.0f), searchSourceBuilder.indexBoosts().get(1));
+                assertWarnings("Object format in indices_boost is deprecated, please use array format instead");
+            }
+        }
+
         {
             String restContent = "{" +
                 "    \"indices_boost\" : [\n" +