public String nextValue() {
            if (this.currentIndex == this.values.length) {
                throw new IllegalStateException("No values remaining for attribute");
            }
            val value = this.values[this.currentIndex].toString();
            this.currentIndex++;
            return value;
        }
Retrieve the next value, by incrementing the current index.

@return the string
@throws IllegalStateException if no values are remaining.
support/cas-server-support-x509-core/src/main/java/org/apereo/cas/adaptors/x509/authentication/principal/X509SubjectPrincipalResolver.java