/*
 * Copyright 2015, TeamDev Ltd. All rights reserved.
 *
 * Redistribution and use in source and/or binary forms, with or without
 * modification, must retain the above copyright notice and the following
 * disclaimer.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.spine3.server.storage;

import com.google.protobuf.Message;

import javax.annotation.Nullable;

/**
 * An entity storage keeps messages with identity.
 *
 * @param <I> the type of entity IDs
 * @param <M> the type of entity state messages written in the storage
 * @author Alexander Yevsyukov
 */
@SuppressWarnings("ClassMayBeInterface")
public abstract class EntityStorage<I, M extends Message> {

    /**
     * Reads message from the storage by the ID.
     *
     * @param id the ID of the message to load
     * @return a message instance or {@code null} if there is no message with such ID
     */
    @Nullable
    public abstract M read(I id);

    /**
     * Writes message into the storage. Rewrites it if the message with such ID already exists.
     *
     * @param id ID of the message
     * @param message the message to save
     * @throws java.lang.NullPointerException if id or message is null
     */
    public abstract void write(I id, M message);
}

/*
 * Copyright 2015, TeamDev Ltd. All rights reserved.
 *
 * Redistribution and use in source and/or binary forms, with or without
 * modification, must retain the above copyright notice and the following
 * disclaimer.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.spine3.server.storage;

import com.google.protobuf.Message;

import javax.annotation.Nullable;

/**
 * An entity storage keeps messages with identity.
 *
 * @param <I> the type of entity IDs
 * @param <M> the type of entity state messages written in the storage
 * @author Alexander Yevsyukov
 */
@SuppressWarnings("ClassMayBeInterface")
public abstract class EntityStorage<I, M extends Message> {

    /**
     * Reads a message from the storage by the ID.
     *
     * @param id the ID of the message to load
     * @return a message instance or {@code null} if there is no message with such ID
     */
    @Nullable
    public abstract M read(I id);

    /**
     * Writes a message into the storage. Rewrites it if the message with such ID already exists.
     *
     * @param id ID of the message
     * @param message the message to save
     * @throws java.lang.NullPointerException if id or message is null
     */
    public abstract void write(I id, M message);
}

Fix docs.