return newArray;
    }

    /**
     * Returns an array that is the concatenation of two arrays.
     * <p>
     * If either or both arrays are {@literal null}, the other array is returned as is.
     * If either or both arrays have a length of {@literal 0}, the other array is returned as is.
     * In any case, the returned array is the same instance as the argument array and is not copied.
     * </p>

    /**
     * Do not instantiate.
     */
    protected ObjectUtil() {
    }

    /**
     * Returns true if the two objects are equal, or both are null.
     *
     * @param object1 the first object
     * @param object2 the second object
     * @return true if equal or both null, false otherwise
     */
    public static boolean equals(final Object object1, final Object object2) {
        if (object1 == object2) {

    }

    /**
     * Registers a data store instance with the factory using the specified name.
     * The data store will be accessible by both the provided name and its class simple name,
     * both converted to lowercase for case-insensitive lookup.
     *
     * @param name the name to register the data store under, must not be null

        assertEquals(message, exception.getMessage());
        assertNull(exception.getCause());
    }

    public void test_constructor_withNullMessageAndCause() {
        // Test constructor with both null message and cause
        FessSystemException exception = new FessSystemException(null, null);

        assertNull(exception.getMessage());
        assertNull(exception.getCause());
    }

 * text during indexing and search operations.
 *
 * <p>Each mapping item consists of one or more input character sequences that are mapped to a single output
 * character sequence. The mapping supports both original values and new values for update operations.</p>
 */
public class CharMappingItem extends DictionaryItem {
    /**
     * Array of input character sequences that will be mapped to the output sequence.

import org.jspecify.annotations.Nullable;

/**
 * To be implemented by test generators of things that can contain elements. Such things include
 * both {@link Collection} and {@link Map}; since there isn't an established collective noun that
 * encompasses both of these, 'container' is used.
 *
 * @author George van den Driessche
 */
@GwtCompatible
@NullMarked

   *
   * <p>To ensure that the created instance obeys its contract, the parameters should satisfy the
   * following constraints. This is the callers responsibility and is not enforced here.
   *
   * <ul>
   *   <li>Both {@code xStats} and {@code yStats} must have the same {@code count}.
   *   <li>If that {@code count} is 1, {@code sumOfProductsOfDeltas} must be exactly 0.0.

  public void testRoundToDouble_twoToThe54PlusOne() {
    double twoToThe54 = Math.pow(2, 54);
    // the representable doubles are 2^54 and 2^54 + 4
    // 2^54+1 is less than halfway between, so HALF_DOWN and HALF_UP will both go down.
    new RoundToDoubleTester(BigDecimal.valueOf((1L << 54) + 1))
        .setExpectation(twoToThe54, DOWN, FLOOR, HALF_DOWN, HALF_UP, HALF_EVEN)
        .setExpectation(Math.nextUp(twoToThe54), CEILING, UP)

   */
  Map<K, V> entriesOnlyOnRight();

  /**
   * Returns an unmodifiable map containing the entries that appear in both maps; that is, the
   * intersection of the two maps.
   */
  Map<K, V> entriesInCommon();

  /**
   * Returns an unmodifiable map describing keys that appear in both maps, but with different
   * values.
   */
  Map<K, ValueDifference<V>> entriesDiffering();

  /**

  /**
   * Determines whether two possibly-null objects are equal. Returns:
   *
   * <ul>
   *   <li>{@code true} if {@code a} and {@code b} are both null.
   *   <li>{@code true} if {@code a} and {@code b} are both non-null and they are equal according to
   *       {@link Object#equals(Object)}.
   *   <li>{@code false} in all other situations.
   * </ul>
   *