public SamlServiceProviderBuilder sloHandler(SamlSingleLogoutHandler sloHandler) {
        this.sloHandler = requireNonNull(sloHandler, "sloHandler");
        return this;
    }
Sets a {@link SamlSingleLogoutHandler} which handles SAML messages for a single sign-on.
saml/src/main/java/com/linecorp/armeria/server/saml/SamlServiceProviderBuilder.java