get a list of strings that corresponds to the issuer regular expression constraints from a jaxb certificateconstraintstype concode_field_sep PlaceHolder placeHolder concode_field_sep CertConstraints createCertConstraints concode_elem_sep List<String> getSubjectConstraints concode_elem_sep CertConstraints.Combinator getSubjectConstraintsCombinator concode_elem_sep CertConstraints.Combinator getIssuerConstraintsCombinator