Remove final complex methods

server/src/main/java/org/elasticsearch/cluster/ClusterState.java

@@ -759,10 +759,8 @@ public Iterator<? extends ToXContent> toXContentChunked(ToXContent.Params outerP
 
             // customs
             metrics.contains(Metric.CUSTOMS)
-                ? Iterators.flatMap(
-                    customs.entrySet().iterator(),
-                    cursor -> ChunkedToXContentHelper.wrapWithObject(cursor.getKey(), cursor.getValue().toXContentChunked(outerParams))
-                )
+                ? ChunkedToXContent.builder(outerParams)
+                    .forEach(customs.entrySet().iterator(), (b, e) -> b.xContentObject(e.getKey(), e.getValue()))
                 : Collections.emptyIterator()
         );
     }

server/src/main/java/org/elasticsearch/common/xcontent/ChunkedToXContentBuilder.java

@@ -263,6 +263,16 @@ public <T> ChunkedToXContentBuilder array(Iterator<T> items, BiConsumer<ChunkedT
         return this;
     }
 
+    /**
+     * Creates an array with the contents set by appending together the contents of {@code items}
+     */
+    public ChunkedToXContentBuilder array(Iterator<? extends ToXContent> items) {
+        startArray();
+        items.forEachRemaining(this::append);
+        endArray();
+        return this;
+    }
+
     /**
      * Creates an array, with the contents set by appending together
      * the return values of {@code create} called on each item returned by {@code items}

server/src/main/java/org/elasticsearch/common/xcontent/ChunkedToXContentHelper.java

@@ -53,26 +53,10 @@ public static Iterator<ToXContent> field(String name, String value) {
         return Iterators.single(((builder, params) -> builder.field(name, value)));
     }
 
-    /**
-     * Creates an Iterator to serialize a named field where the value is represented by a {@link ChunkedToXContentObject}.
-     * Chunked equivalent for {@code XContentBuilder field(String name, ToXContent value)}
-     * @param name name of the field
-     * @param value value for this field
-     * @param params params to propagate for XContent serialization
-     * @return Iterator composing field name and value serialization
-     */
-    public static Iterator<ToXContent> field(String name, ChunkedToXContentObject value, ToXContent.Params params) {
-        return Iterators.concat(Iterators.single((builder, innerParam) -> builder.field(name)), value.toXContentChunked(params));
-    }
-
     public static Iterator<ToXContent> array(String name, Iterator<? extends ToXContent> contents) {
         return Iterators.concat(ChunkedToXContentHelper.startArray(name), contents, ChunkedToXContentHelper.endArray());
     }
 
-    public static <T extends ToXContent> Iterator<ToXContent> wrapWithObject(String name, Iterator<T> iterator) {
-        return Iterators.concat(startObject(name), iterator, endObject());
-    }
-
     /**
      * Creates an Iterator of a single ToXContent object that serializes the given object as a single chunk. Just wraps {@link
      * Iterators#single}, but still useful because it avoids any type ambiguity.

server/src/test/java/org/elasticsearch/common/xcontent/ChunkedToXContentBuilderTests.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.common.xcontent;
+
+import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.collect.Iterators;
+import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.xcontent.ToXContent;
+
+import java.util.function.IntFunction;
+import java.util.stream.IntStream;
+
+import static org.hamcrest.Matchers.equalTo;
+
+public class ChunkedToXContentBuilderTests extends ESTestCase {
+
+    public void testFieldWithInnerChunkedObject() {
+
+        ToXContent innerXContent = (b, p) -> {
+            b.startObject();
+            b.field("field1", 10);
+            b.field("field2", "aaa");
+            b.endObject();
+            return b;
+        };
+
+        ToXContent outerXContent = (b, p) -> b.field("field3", 10).field("field4", innerXContent);
+
+        String expectedContent = Strings.toString(outerXContent);
+
+        ChunkedToXContentObject innerChunkedContent = params -> new ChunkedToXContentBuilder(params).object(
+            o -> o.field("field1", 10).field("field2", "aaa")
+        );
+
+        ChunkedToXContent outerChunkedContent = params -> new ChunkedToXContentBuilder(params).field("field3", 10)
+            .field("field4", innerChunkedContent);
+
+        assertThat(Strings.toString(outerChunkedContent), equalTo(expectedContent));
+    }
+
+    public void testFieldWithInnerChunkedArray() {
+
+        ToXContent innerXContent = (b, p) -> {
+            b.startArray();
+            b.value(10);
+            b.value(20);
+            b.endArray();
+            return b;
+        };
+
+        ToXContent outerXContent = (b, p) -> b.field("field3", 10).field("field4", innerXContent);
+
+        String expectedContent = Strings.toString(outerXContent);
+
+        IntFunction<ToXContent> value = v -> (b, p) -> b.value(v);
+
+        ChunkedToXContentObject innerChunkedContent = params -> new ChunkedToXContentBuilder(params).array(
+            IntStream.of(10, 20).mapToObj(value).iterator()
+        );
+
+        ChunkedToXContent outerChunkedContent = params -> new ChunkedToXContentBuilder(params).field("field3", 10)
+            .field("field4", innerChunkedContent);
+
+        assertThat(Strings.toString(outerChunkedContent), equalTo(expectedContent));
+    }
+
+    public void testFieldWithInnerChunkedField() {
+
+        ToXContent innerXContent = (b, p) -> b.value(10);
+        ToXContent outerXContent = (b, p) -> b.field("field3", 10).field("field4", innerXContent);
+
+        String expectedContent = Strings.toString(outerXContent);
+
+        ChunkedToXContentObject innerChunkedContent = params -> Iterators.single((b, p) -> b.value(10));
+
+        ChunkedToXContent outerChunkedContent = params -> new ChunkedToXContentBuilder(params).field("field3", 10)
+            .field("field4", innerChunkedContent);
+
+        assertThat(Strings.toString(outerChunkedContent), equalTo(expectedContent));
+    }
+}

x-pack/plugin/shutdown/src/main/java/org/elasticsearch/xpack/shutdown/SingleNodeShutdownStatus.java

@@ -12,11 +12,10 @@
 import org.elasticsearch.cluster.metadata.ShutdownShardMigrationStatus;
 import org.elasticsearch.cluster.metadata.SingleNodeShutdownMetadata;
 import org.elasticsearch.common.Strings;
-import org.elasticsearch.common.collect.Iterators;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ChunkedToXContentHelper;
+import org.elasticsearch.common.xcontent.ChunkedToXContent;
 import org.elasticsearch.common.xcontent.ChunkedToXContentObject;
 import org.elasticsearch.xcontent.ParseField;
 import org.elasticsearch.xcontent.ToXContent;
@@ -25,10 +24,6 @@
 import java.util.Iterator;
 import java.util.Objects;
 
-import static org.elasticsearch.common.xcontent.ChunkedToXContentHelper.endObject;
-import static org.elasticsearch.common.xcontent.ChunkedToXContentHelper.singleChunk;
-import static org.elasticsearch.common.xcontent.ChunkedToXContentHelper.startObject;
-
 public class SingleNodeShutdownStatus implements Writeable, ChunkedToXContentObject {
 
     private final SingleNodeShutdownMetadata metadata;
@@ -116,26 +111,27 @@ public String toString() {
 
     @Override
     public Iterator<? extends ToXContent> toXContentChunked(ToXContent.Params params) {
-        return Iterators.concat(startObject(), singleChunk((builder, p) -> {
-            builder.field(SingleNodeShutdownMetadata.NODE_ID_FIELD.getPreferredName(), metadata.getNodeId());
-            builder.field(SingleNodeShutdownMetadata.TYPE_FIELD.getPreferredName(), metadata.getType());
-            builder.field(SingleNodeShutdownMetadata.REASON_FIELD.getPreferredName(), metadata.getReason());
-            if (metadata.getAllocationDelay() != null) {
-                builder.field(
-                    SingleNodeShutdownMetadata.ALLOCATION_DELAY_FIELD.getPreferredName(),
-                    metadata.getAllocationDelay().getStringRep()
+        return ChunkedToXContent.builder(params).object(b -> {
+            b.append((builder, p) -> {
+                builder.field(SingleNodeShutdownMetadata.NODE_ID_FIELD.getPreferredName(), metadata.getNodeId());
+                builder.field(SingleNodeShutdownMetadata.TYPE_FIELD.getPreferredName(), metadata.getType());
+                builder.field(SingleNodeShutdownMetadata.REASON_FIELD.getPreferredName(), metadata.getReason());
+                if (metadata.getAllocationDelay() != null) {
+                    builder.field(
+                        SingleNodeShutdownMetadata.ALLOCATION_DELAY_FIELD.getPreferredName(),
+                        metadata.getAllocationDelay().getStringRep()
+                    );
+                }
+                builder.timeField(
+                    SingleNodeShutdownMetadata.STARTED_AT_MILLIS_FIELD.getPreferredName(),
+                    SingleNodeShutdownMetadata.STARTED_AT_READABLE_FIELD,
+                    metadata.getStartedAtMillis()
                 );
-            }
-            builder.timeField(
-                SingleNodeShutdownMetadata.STARTED_AT_MILLIS_FIELD.getPreferredName(),
-                SingleNodeShutdownMetadata.STARTED_AT_READABLE_FIELD,
-                metadata.getStartedAtMillis()
-            );
-            builder.field(STATUS.getPreferredName(), overallStatus());
-            return builder;
-        }),
-            ChunkedToXContentHelper.field(SHARD_MIGRATION_FIELD.getPreferredName(), shardMigrationStatus, params),
-            singleChunk((builder, p) -> {
+                builder.field(STATUS.getPreferredName(), overallStatus());
+                return builder;
+            });
+            b.field(SHARD_MIGRATION_FIELD.getPreferredName(), shardMigrationStatus);
+            b.append((builder, p) -> {
                 builder.field(PERSISTENT_TASKS_FIELD.getPreferredName(), persistentTasksStatus);
                 builder.field(PLUGINS_STATUS.getPreferredName(), pluginsStatus);
                 if (metadata.getTargetNodeName() != null) {
@@ -148,8 +144,7 @@ public Iterator<? extends ToXContent> toXContentChunked(ToXContent.Params params
                     );
                 }
                 return builder;
-            }),
-            endObject()
-        );
+            });
+        });
     }
 }