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This library focuses on providing different flavors of eventsourced aggregrates

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/*
 * Copyright 2021-2024 the original author or authors.
 *
 * 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
 *
 *      https://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 dk.cloudcreate.essentials.components.eventsourced.aggregates.decider;

/**
 * {@link Decider} or {@link View} related interface, which provides the Initial STATE for a given  aggregate/projection/view.

 * The {@link InitialStateProvider} works in collaboration with the {@link StateEvolver} in the context of
 * the {@link Decider} or {@link View} pattern
 *
 * @param  The type of aggregate/projection/view STATE provided
 */
public interface InitialStateProvider {
    /**
     * The initial aggregate/projection/view STATE before any EVENT's have been applied / projected onto the aggregate/projection/view STATE

     * Note: The default implementation returns a null aggregate/projection/view STATE
     *
     * @return the initial projection/view STATE. May be null
     */
    default STATE initialState() {
        return null;
    }
}