public SamlIdentityProviderConfigBuilder nameIdPolicy(SamlNameIdPolicy nameIdPolicy) {
        this.nameIdPolicy = requireNonNull(nameIdPolicy, "nameIdPolicy");
        return this;
    }
Sets a {@link SamlNameIdPolicy} to configure an {@link AuthnRequest}.
saml/src/main/java/com/linecorp/armeria/server/saml/SamlIdentityProviderConfigBuilder.java