code: public static <T> T[] concat(@NullableDecl T element, T[] array) {
      T[] result = newArray(array, array.length + 1);
      result[0] = element;
      System.arraycopy(array, 0, result, 1, array.length);
      return result;
    }
docs: Returns a new array that prepends {@code element} to {@code array}.
  
  @param element the element to prepend to the front of {@code array}
  @param array the array of elements to append
  @return an array whose size is one larger than {@code array}, with {@code element} occupying
  the first position, and the elements of {@code array} occupying the remaining elements.