src/java/org/apache/poi/common/Duplicatable.java

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package org.apache.poi.common;

/**
 * This is an alternative to the {@link Cloneable} interface without its side-effects.
 * A class implementing Duplicatable provides a deep-copy of itself - usually this is done via a copy-constructor,
 * which is invoked with a self-reference by the copy method.
 * References to child objects are duplicated - references to parents are kept as-is and
 * might need to be replaced by the parent copy operation.
 *
 * @see <a href="https://www.artima.com/intv/bloch.html#part13">Copy Constructor versus Cloning</a>
 */
public interface Duplicatable {
    // Providing a generics interface Duplicatable<T extends Duplicatable<T>> pushes too many
    // changes to the implementing classes and the benefit of providing a subtype-specific copy method
    // is not sufficient
    /**
     * @return a deep copy of the implementing class / instance
     */
    Duplicatable copy();
}