docs: public static String[] concatenateStringArrays(String[] array1,
                                                     String[] array2) {
          if (isEmpty(array1)) {
              return array2;
          }
          if (isEmpty(array2)) {
              return array1;
          }
          String[] newArr = new String[array1.length + array2.length];
          System.arraycopy(array1, 0, newArr, 0, array1.length);
          System.arraycopy(array2, 0, newArr, array1.length, array2.length);
          return newArr;
      }