### Question:
ArrayUtil { @Deprecated public static <T> T[] concat( T first, T... additional ) { @SuppressWarnings( "unchecked" ) T[] result = (T[]) Array.newInstance( additional.getClass().getComponentType(), additional.length + 1 ); result[0] = first; System.arraycopy( additional, 0, result, 1, additional.length ); return result; } private  ArrayUtil(); @Deprecated static int hashCode( Object array ); @Deprecated static boolean equals( Object firstArray, Object otherArray ); @Deprecated static boolean equals( Object firstArray, Object otherArray, ArrayEquality equality ); @Deprecated static Object clone( Object array ); @Deprecated static int missing( T[] array, T[] contains ); @Deprecated static boolean containsAll( T[] array, T[] contains ); @Deprecated static boolean contains( T[] array, T contains ); @Deprecated static boolean contains( T[] array, int arrayLength, T contains ); @Deprecated static boolean nullSafeEquals( T first, T other ); @Deprecated static T[] union( T[] first, T[] other ); @Deprecated static boolean isEmpty( Object[] array ); @Deprecated static String join( T[] items, String delimiter ); @Deprecated static TO[] map( FROM[] from, Function<FROM,TO> transformer, Class<TO> toClass ); @Deprecated static T[] concat( T first, T... additional ); @Deprecated static T[] concat( T[] initial, T... additional ); static T[] concatArrays( T[] initial, T[]... additional ); @Deprecated @SafeVarargs static T[] array( T... varargs ); @Deprecated static T lastOf( T[] array ); @Deprecated static int indexOf( T[] array, T item ); @Deprecated static T[] without( T[] source, T... toRemove ); @Deprecated static void reverse( T[] array ); @Deprecated
    static final ArrayEquality DEFAULT_ARRAY_EQUALITY; @Deprecated
    static final ArrayEquality BOXING_AWARE_ARRAY_EQUALITY; }### Answer:
@Test void shouldConcatOneAndMany() { Integer[] result = ArrayUtil.concat( 0, 1, 2, 3, 4 ); for ( int i = 0; i < 5; i++ ) { assertEquals( (Integer)i, result[i] ); } }
@Test void shouldConcatArrays() { Integer[] initial = new Integer[] {0, 1, 2}; Integer[] all = ArrayUtil.concat( initial, 3, 4, 5 ); assertArrayEquals( new Integer[] {0, 1, 2, 3, 4, 5}, all ); }