This field:
https://github.com/odoo/odoo/blob/625a648f227325468981a9e4a51e80b44132a45f/addons/stock/models/stock_move_line.py#L40

Allways shows the same value as create_date.

Could it be defined as stock.move related field?

Should it be written here?
https://github.com/odoo/odoo/blob/3c0337673385876922da95296e70a0b7b728f275/addons/stock/models/stock_move.py#L1048

@Tecnativa
from collections import Counter
from odoo import api, fields, models, _
from odoo.addons import decimal_precision as dp
from odoo.exceptions import UserError, ValidationError
from odoo.tools.pycompat import izip
from odoo.tools.float_utils import float_round, float_compare, float_is_zero
class StockMoveLine(models.Model):
    _name = "stock.move.line"
    _description = "Packing Operation"
    _rec_name = "product_id"
    _order = "result_package_id desc, id"
    picking_id = fields.Many2one(
        'stock.picking', 'Stock Picking',
        help='The stock operation where the packing has been made')
    move_id = fields.Many2one(
        'stock.move', 'Stock Move',
        help="Change to a better name")
    product_id = fields.Many2one('product.product', 'Product', ondelete="cascade")