in scim-spec/scim-spec-schema/src/main/java/org/apache/directory/scim/spec/resources/PhoneNumber.java [484:496]
public LocalPhoneNumberBuilder countryCode(String countryCode) {
String localCode = countryCode;
if (localCode != null && !localCode.isEmpty()) {
localCode = localCode.trim();
if (localCode.length() > 0 && localCode.charAt(0) != '+') {
localCode = '+' + localCode;
}
}
this.countryCode = localCode;
return this;
}