private List<Object> getUsernameAttributeValues(final Map<String, List<Object>> query) {
        if (query.containsKey(this.usernameAttribute)) {
            val usernameAttributeValues = query.get(this.usernameAttribute);
            LOGGER.debug("Using [{}] attribute to get username from the query map", this.usernameAttribute);
            return usernameAttributeValues;
        }
        val usernameAttributeValues = query.get(DEFAULT_USERNAME_ATTRIBUTE);
        LOGGER.debug("Using [{}] attribute to get username from the query map", DEFAULT_USERNAME_ATTRIBUTE);
        return usernameAttributeValues;
    }
Provides the username attribute based on a pre-configured string. Determines the username from a query Map based
on the configured attribute, {@link StringUtils#trimToNull(String)}, and if the username value does not contain a
wildcard.

@author Eric Dalquist
@since 7.1.0
core/cas-server-core-authentication-api/src/main/java/org/apereo/cas/authentication/attribute/SimpleUsernameAttributeProvider.java