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SDK for the development of HiveMQ Kafka Extension customizations

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/*
 * Copyright 2020-present HiveMQ GmbH
 *
 * Licensed 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 com.hivemq.extensions.kafka.api.transformers.kafkatomqtt;

import com.hivemq.extension.sdk.api.annotations.DoNotImplement;
import com.hivemq.extension.sdk.api.annotations.NotNull;
import com.hivemq.extension.sdk.api.services.builder.PublishBuilder;
import com.hivemq.extension.sdk.api.services.publish.Publish;

import java.util.List;

/**
 * The output parameter of the {@link KafkaToMqttTransformer}. It allows access to the {@link PublishBuilder}.
 * 
 * After the {@link KafkaToMqttTransformer#transformKafkaToMqtt(KafkaToMqttInput, KafkaToMqttOutput)} method returns the
 * {@link Publish}es given to this output will be published by HiveMQ.
 *
 * @author Christoph Schäbel
 * @author Georg Held
 * @since 4.5.0
 */
@DoNotImplement
public interface KafkaToMqttOutput {

    /**
     * @return A new {@link PublishBuilder}.
     * @since 4.5.0
     */
    @NotNull PublishBuilder newPublishBuilder();

    /**
     * Sets the {@link Publish}es, that will be published by HiveMQ after the {@link
     * KafkaToMqttTransformer#transformKafkaToMqtt(KafkaToMqttInput, KafkaToMqttOutput)} call returns. The "HiveMQ
     * Enterprise Extension for Kafka" will publish these publishes in the order provided by the {@code publishes}
     * argument.
     * 

     * If desired, the same publish can occupy multiple places in the {@code publishes} list. When no publish shall be
     * published by HiveMQ for a {@link com.hivemq.extensions.kafka.api.model.KafkaRecord}, call this method with an
     * empty list.
     * 

     * Use the {@link #newPublishBuilder() PublishBuilder} to create new publishes as desired.
     * 
     * Each additional call of this method will overwrite the previous one.
     *
     * @param publishes A list of to be published {@link Publish}es.
     * @throws NullPointerException     If {@code publishes} or any element of it is null.
     * @throws IllegalArgumentException If any element in {@code publishes} was not created via a {@link
     *                                  PublishBuilder}.
     * @since 4.5.0
     */
    void setPublishes(@NotNull List<@NotNull Publish> publishes);
}