* }
   * }
   *
   * <p>Note that if any input list is empty, the Cartesian product will also be empty. If no lists
   * at all are provided (an empty list), the resulting Cartesian product has one element, an empty
   * list (counter-intuitive, but mathematically consistent).
   *
   * <p><i>Performance notes:</i> while the cartesian product of lists of size {@code m, n, p} is a

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * 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,

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * 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,

    /** createdBy */
    protected String createdBy;

    /** createdTime */
    protected Long createdTime;

    /** generator */
    protected String generator;

    /** path */
    protected String path;

    /** target */
    protected String target;

    /** thumbnail_id */
    protected String thumbnailId;

    // [Referrers] *comment only

        }
        return _specification;
    }

    protected void assertQueryPurpose() {
    }

    protected void assertAggregationPurpose() {
    }

    protected void assertSpecifyPurpose() {
    }

    public static class HpSpecification {
        protected List<String> columnList = new ArrayList<>();

        public void doColumn(String name) {

        }
        return _specification;
    }

    protected void assertQueryPurpose() {
    }

    protected void assertAggregationPurpose() {
    }

    protected void assertSpecifyPurpose() {
    }

    public static class HpSpecification {
        protected List<String> columnList = new ArrayList<>();

        public void doColumn(String name) {

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * 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,

    private static final Logger logger = LogManager.getLogger(FessUrlQueueService.class);

    /** Configuration value for sequential URL processing order */
    protected static final String ORDER_SEQUENTIAL = "sequential";

    /** Configuration value for random URL processing order */
    protected static final String ORDER_RANDOM = "random";

    /**
     * Constructs a new FessUrlQueueService with the specified crawler configuration.
     *

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * 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,

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * 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,