protected String toResourceString(final Object credential) {
        val auditFormat = AuditFormats.valueOf(properties.getAuditFormat().name());
        return auditFormat.serialize(credential);
    }
Converts the Credential object into a String resource identifier.

@author Scott Battaglia
@since 3.1.2
core/cas-server-core-audit-api/src/main/java/org/apereo/cas/audit/spi/resource/CredentialsAsFirstParameterResourceResolver.java