39It is true that, according to the Court’s case-law, cleaning services, such as those at issue in the dispute in the main proceedings, can be regarded as an activity essentially based on manpower (see, to that effect, Hernández Vidal and Others, paragraph 27; Hidalgo and Others, paragraph 26; and Jouini and Others, paragraph 32) and, consequently, a group of employees who are permanently assigned to the common task of cleaning may, in the absence of other factors of production, amount to an economic entity (see, to that effect, Hernández Vidal and Others, paragraph 27). That entity’s identity must nonetheless be retained after the transfer in question.