See super class satosa.backends.backend_base.BackendModule#get_metadata_desc
        :rtype: satosa.metadata_creation.description.MetadataDescription

def get_metadata_desc(self):
        """
        See super class satosa.backends.backend_base.BackendModule#get_metadata_desc
        :rtype: satosa.metadata_creation.description.MetadataDescription
        """
        entity_descriptions = []

        idp_entities = self.sp.metadata.with_descriptor("idpsso")
        for entity_id, entity in idp_entities.items():
            description = MetadataDescription(urlsafe_b64encode(entity_id.encode("utf-8")).decode("utf-8"))

            # Add organization info
            try:
                organization_info = entity["organization"]
            except KeyError:
                pass
            else:
                organization = OrganizationDesc()
                for name_info in organization_info.get("organization_name", []):
                    organization.add_name(name_info["text"], name_info["lang"])
                for display_name_info in organization_info.get("organization_display_name", []):
                    organization.add_display_name(display_name_info["text"], display_name_info["lang"])
                for url_info in organization_info.get("organization_url", []):
                    organization.add_url(url_info["text"], url_info["lang"])
                description.organization = organization

            # Add contact person info
            try:
                contact_persons = entity["contact_person"]
            except KeyError:
                pass
            else:
                for person in contact_persons:
                    person_desc = ContactPersonDesc()
                    person_desc.contact_type = person.get("contact_type")
                    for address in person.get('email_address', []):
                        person_desc.add_email_address(address["text"])
                    if "given_name" in person:
                        person_desc.given_name = person["given_name"]["text"]
                    if "sur_name" in person:
                        person_desc.sur_name = person["sur_name"]["text"]

                    description.add_contact_person(person_desc)

            # Add UI info
            ui_info = self.sp.metadata.extension(entity_id, "idpsso_descriptor", "{}&UIInfo".format(UI_NAMESPACE))
            if ui_info:
                ui_info = ui_info[0]
                ui_info_desc = UIInfoDesc()
                for desc in ui_info.get("description", []):
                    ui_info_desc.add_description(desc["text"], desc["lang"])
                for name in ui_info.get("display_name", []):
                    ui_info_desc.add_display_name(name["text"], name["lang"])
                for logo in ui_info.get("logo", []):
                    ui_info_desc.add_logo(logo["text"], logo["width"], logo["height"], logo.get("lang"))
                description.ui_info = ui_info_desc

            entity_descriptions.append(description)
        return entity_descriptions