protected Set<Object> getPrincipalAttributeValues(final Principal principal,
                                                      final String attributeName) {
        val attributes = principal.getAttributes();
        if (attributes.containsKey(attributeName)) {
            return CollectionUtils.toCollection(attributes.get(attributeName));
        }
        return Set.of();
    }
This is {@link DefaultScimPrincipalAttributeMapper}.

@author Misagh Moayyed
@since 5.1.0
support/cas-server-support-scim-core/src/main/java/org/apereo/cas/scim/v2/provisioning/DefaultScimPrincipalAttributeMapper.java