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 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.elasticsearch.search.aggregations.metrics.percentiles.hdr;

import org.HdrHistogram.DoubleHistogram;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.search.DocValueFormat;
import org.elasticsearch.search.aggregations.metrics.percentiles.Percentile;
import org.elasticsearch.search.aggregations.metrics.percentiles.Percentiles;
import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;

import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

public class InternalHDRPercentiles extends AbstractInternalHDRPercentiles implements Percentiles {
    public static final String NAME = "hdr_percentiles";

    public InternalHDRPercentiles(String name, double[] percents, DoubleHistogram state, boolean keyed, DocValueFormat formatter,
            List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData) {
        super(name, percents, state, keyed, formatter, pipelineAggregators, metaData);
    }

    /**
     * Read from a stream.
     */
    public InternalHDRPercentiles(StreamInput in) throws IOException {
        super(in);
    }

    @Override
    public String getWriteableName() {
        return NAME;
    }

    @Override
    public Iterator<Percentile> iterator() {
        return new Iter(keys, state);
    }

    @Override
    public double percentile(double percent) {
        if (state.getTotalCount() == 0) {
            return Double.NaN;
        }
        return state.getValueAtPercentile(percent);
    }

    @Override
    public String percentileAsString(double percent) {
        return valueAsString(String.valueOf(percent));
    }

    @Override
    public double value(double key) {
        return percentile(key);
    }

    @Override
    protected AbstractInternalHDRPercentiles createReduced(String name, double[] keys, DoubleHistogram merged, boolean keyed,
            List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData) {
        return new InternalHDRPercentiles(name, keys, merged, keyed, format, pipelineAggregators, metaData);
    }

    public static class Iter implements Iterator<Percentile> {

        private final double[] percents;
        private final DoubleHistogram state;
        private int i;

        public Iter(double[] percents, DoubleHistogram state) {
            this.percents = percents;
            this.state = state;
            i = 0;
        }

        @Override
        public boolean hasNext() {
            return i < percents.length;
        }

        @Override
        public Percentile next() {
            final Percentile next = new Percentile(percents[i], state.getValueAtPercentile(percents[i]));
            ++i;
            return next;
        }

        @Override
        public final void remove() {
            throw new UnsupportedOperationException();
        }
    }
}

@@ -3408,76 +3408,186 @@
     
-final Percentile next = new Percentile(percents%5Bi%5D, state.getValueAt
+double percent = percents%5Bi%5D;%0A            double value = (state.getTotalCount() == 0) ? Double.NaN : state.getValueAtPercentile(percent);%0A            final Percentile next = new 
 Perc
@@ -3604,13 +3604,15 @@
 cent
-s%5Bi%5D)
+, value
 );%0A 

Align behavior of HDR percentiles iterator with percentile() method (#24206)