Identity Provider mapper to get nested objects values in json array

Getting advice
1

Hello there,
I’m using the Identity Provider “ProSanteConnect” ( GitHub - ansforge/keycloak-prosanteconnect: Provider Keycloak pour Pro Santé Connect ) and the generated access token looks like this :

{
    "Secteur_Activite": "",
    "sub": "sub",
    "SubjectOrganization": "str",
    "Mode_Acces_Raison": "",
    "preferred_username": "str",
    "codeCivilite": "M",
    "given_name": "Paul",
    "SubjectNameID": "str",
    "family_name": "NOM",
    "Acces_Regulation_Medicale": "FAUX",
    "UITVersion": "1.0",
    "Palier_Authentification": "APPPRIP3^1....",
    "SubjectRefPro": {
        "exercices": [
          {
            "codeProfession": "21",
            "codeCategorieProfessionnelle": "C",
            "codeCiviliteDexercice": "DR",
            "nomDexercice": "PHARMACIEN0023701",
            "prenomDexercice": "FRANCOISE",
            "codeTypeSavoirFaire": "",
            "codeSavoirFaire": "",
            "activities": [
              {
                "codeModeExercice": "L",
                "codeSecteurDactivite": "SA33",
                "codeSectionPharmacien": "A",
                "codeRole": "",
                "codeGenreActivite": "GENR01",
                "numeroSiretSite": "",
                "numeroSirenSite": "",
                "numeroFinessSite": "0B0135257",
                "numeroFinessetablissementJuridique": "",
                "identifiantTechniqueDeLaStructure": "F0B0135257",
                "raisonSocialeSite": "PHARMACIE DU CENTRE13525",
                "enseigneCommercialeSite": "",
                "complementDestinataire": "PHARMACIE DU CENTRE",
                "complementPointGeographique": "",
                "numeroVoie": "3",
                "indiceRepetitionVoie": "",
                "codeTypeDeVoie": "R",
                "libelleVoie": "DE CHATEAUDUN",
                "mentionDistribution": "",
                "bureauCedex": "75009 PARIS",
                "codePostal": "75009",
                "codeCommune": "",
                "codePays": "99000",
                "telephone": "",
                "telephone2": "",
                "telecopie": "",
                "adresseEMail": "",
                "codeDepartement": "",
                "ancienIdentifiantDeLaStructure": "10B0135257",
                "autoriteDenregistrement": "CNOP/CNOP/ARS + CNOP"
              }
            ]
          }
        ]
    },
    "SubjectOrganizationID": "",
    "SubjectRole": [
        "10^1.2.250.1.213.1.1.5.5"
    ],
    "PSI_Locale": "1.2.250.1.213.1.3.1.1",
    "otherIds": [
        {
            "identifiant": "ANS20210107161422",
            "origine": "EDIT",
            "qualite": 1
        }
    ]
}

(A user can have multiple “exercices”. Each “exercice” can have many “activities”.)

If I want to save, for example, each “activities[*].codeModeExercice” on one attribute on a user (codesModeExercices=S##L), how can I make it ? Is it possible to do it without developing a custom mapper ?

Thanks !