Use Void context on parsers where possible (#50573)

*Most* of our parsing can be done without passing any extra context into
the parser that isn't already part of the xcontent stream. While I was
looking around at the places that *do* need a context I found a few
places that were declared to need a context but don't actually need it.

modules/reindex/src/main/java/org/elasticsearch/index/reindex/remote/RemoteResponseParsers.java

@@ -124,7 +124,7 @@ final class RemoteResponseParsers {
     /**
      * Parser for {@code failed} shards in the {@code _shards} elements.
      */
-    public static final ConstructingObjectParser<SearchFailure, XContentType> SEARCH_FAILURE_PARSER =
+    public static final ConstructingObjectParser<SearchFailure, Void> SEARCH_FAILURE_PARSER =
             new ConstructingObjectParser<>("failure", true, a -> {
                 int i = 0;
                 String index = (String) a[i++];
@@ -146,7 +146,7 @@ final class RemoteResponseParsers {
         SEARCH_FAILURE_PARSER.declareString(optionalConstructorArg(), new ParseField("node"));
         SEARCH_FAILURE_PARSER.declareField(constructorArg(), (p, c) -> {
             if (p.currentToken() == XContentParser.Token.START_OBJECT) {
-                return ThrowableBuilder.PARSER.apply(p, c);
+                return ThrowableBuilder.PARSER.apply(p, null);
             } else {
                 return p.text();
             }
@@ -157,7 +157,7 @@ final class RemoteResponseParsers {
      * Parser for the {@code _shards} element. Throws everything out except the errors array if there is one. If there isn't one then it
      * parses to an empty list.
      */
-    public static final ConstructingObjectParser<List<Throwable>, XContentType> SHARDS_PARSER =
+    public static final ConstructingObjectParser<List<Throwable>, Void> SHARDS_PARSER =
             new ConstructingObjectParser<>("_shards", true, a -> {
                 @SuppressWarnings("unchecked")
                 List<Throwable> failures = (List<Throwable>) a[0];
@@ -196,20 +196,20 @@ final class RemoteResponseParsers {
                 return new Response(timedOut, failures, totalHits, hits, scroll);
             });
     static {
-        RESPONSE_PARSER.declareObject(optionalConstructorArg(), ThrowableBuilder.PARSER::apply, new ParseField("error"));
+        RESPONSE_PARSER.declareObject(optionalConstructorArg(), (p, c) -> ThrowableBuilder.PARSER.apply(p, null), new ParseField("error"));
         RESPONSE_PARSER.declareBoolean(optionalConstructorArg(), new ParseField("timed_out"));
         RESPONSE_PARSER.declareString(optionalConstructorArg(), new ParseField("_scroll_id"));
         RESPONSE_PARSER.declareObject(optionalConstructorArg(), HITS_PARSER, new ParseField("hits"));
-        RESPONSE_PARSER.declareObject(optionalConstructorArg(), SHARDS_PARSER, new ParseField("_shards"));
+        RESPONSE_PARSER.declareObject(optionalConstructorArg(), (p, c) -> SHARDS_PARSER.apply(p, null), new ParseField("_shards"));
     }
 
     /**
      * Collects stuff about Throwables and attempts to rebuild them.
      */
     public static class ThrowableBuilder {
-        public static final BiFunction<XContentParser, XContentType, Throwable> PARSER;
+        public static final BiFunction<XContentParser, Void, Throwable> PARSER;
         static {
-            ObjectParser<ThrowableBuilder, XContentType> parser = new ObjectParser<>("reason", true, ThrowableBuilder::new);
+            ObjectParser<ThrowableBuilder, Void> parser = new ObjectParser<>("reason", true, ThrowableBuilder::new);
             PARSER = parser.andThen(ThrowableBuilder::build);
             parser.declareString(ThrowableBuilder::setType, new ParseField("type"));
             parser.declareString(ThrowableBuilder::setReason, new ParseField("reason"));

modules/reindex/src/test/java/org/elasticsearch/index/reindex/remote/RemoteResponseParsersTests.java

@@ -24,7 +24,6 @@ import org.elasticsearch.common.util.concurrent.EsRejectedExecutionException;
 import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
-import org.elasticsearch.common.xcontent.XContentType;
 import org.elasticsearch.index.reindex.ScrollableHitSource;
 import org.elasticsearch.test.ESTestCase;
 import org.hamcrest.Matchers;
@@ -43,7 +42,7 @@ public class RemoteResponseParsersTests extends ESTestCase {
         XContentBuilder builder = jsonBuilder();
         failure.toXContent(builder, ToXContent.EMPTY_PARAMS);
         try (XContentParser parser = createParser(builder)) {
-            ScrollableHitSource.SearchFailure parsed = RemoteResponseParsers.SEARCH_FAILURE_PARSER.parse(parser, XContentType.JSON);
+            ScrollableHitSource.SearchFailure parsed = RemoteResponseParsers.SEARCH_FAILURE_PARSER.parse(parser, null);
             assertNotNull(parsed.getReason());
             assertThat(parsed.getReason().getMessage(), Matchers.containsString("exhausted"));
             assertThat(parsed.getReason(), Matchers.instanceOf(EsRejectedExecutionException.class));

x-pack/plugin/search-business-rules/src/main/java/org/elasticsearch/xpack/searchbusinessrules/PinnedQueryBuilder.java

@@ -133,7 +133,7 @@ public class PinnedQueryBuilder extends AbstractQueryBuilder<PinnedQueryBuilder>
     
     
     
-    private static final ConstructingObjectParser<PinnedQueryBuilder, XContentParser> PARSER = new ConstructingObjectParser<>(NAME,
+    private static final ConstructingObjectParser<PinnedQueryBuilder, Void> PARSER = new ConstructingObjectParser<>(NAME,
             a -> 
                 {
                     QueryBuilder organicQuery = (QueryBuilder) a[0];

x-pack/plugin/sql/sql-action/src/main/java/org/elasticsearch/xpack/sql/action/SqlClearCursorRequest.java

@@ -19,16 +19,17 @@ import java.util.Objects;
 
 import static org.elasticsearch.action.ValidateActions.addValidationError;
 import static org.elasticsearch.common.xcontent.ConstructingObjectParser.constructorArg;
+import static org.elasticsearch.common.xcontent.ConstructingObjectParser.optionalConstructorArg;
+import static org.elasticsearch.xpack.sql.action.AbstractSqlQueryRequest.CLIENT_ID;
 import static org.elasticsearch.xpack.sql.action.AbstractSqlQueryRequest.CURSOR;
 import static org.elasticsearch.xpack.sql.action.AbstractSqlQueryRequest.MODE;
-import static org.elasticsearch.xpack.sql.action.AbstractSqlQueryRequest.CLIENT_ID;
 
 /**
  * Request to clean all SQL resources associated with the cursor
  */
 public class SqlClearCursorRequest extends AbstractSqlRequest {
 
-    private static final ConstructingObjectParser<SqlClearCursorRequest, RequestInfo> PARSER =
+    private static final ConstructingObjectParser<SqlClearCursorRequest, Void> PARSER =
         // here the position in "objects" is the same as the fields parser declarations below 
         new ConstructingObjectParser<>(SqlClearCursorAction.NAME, objects -> {
             RequestInfo requestInfo = new RequestInfo(Mode.fromString((String) objects[1]),
@@ -39,8 +40,8 @@ public class SqlClearCursorRequest extends AbstractSqlRequest {
     static {
         // "cursor" is required constructor parameter
         PARSER.declareString(constructorArg(), CURSOR);
-        PARSER.declareString(ConstructingObjectParser.optionalConstructorArg(), MODE);
-        PARSER.declareString(ConstructingObjectParser.optionalConstructorArg(), CLIENT_ID);
+        PARSER.declareString(optionalConstructorArg(), MODE);
+        PARSER.declareString(optionalConstructorArg(), CLIENT_ID);
     }
 
     private String cursor;