protected void validateIssuerIfItExists(final Issuer isser, final SAML2MessageContext context) {
        if (isser != null) {
            validateIssuer(isser, context);
        }
    }
<p>validateIssuerIfItExists.</p>

@param isser a {@link Issuer} object
@param context a {@link SAML2MessageContext} object
pac4j-saml/src/main/java/org/pac4j/saml/profile/impl/AbstractSAML2ResponseValidator.java