in saml-authentication-server/src/main/java/jetbrains/buildServer/auth/saml/plugin/SamlAuthenticationScheme.java [334:341]
public URL getCallbackUrl() throws MalformedURLException {
String result = WebUtil.combineContextPath(rootUrlHolder.getRootUrl(), SamlPluginConstants.SAML_CALLBACK_URL.replace("**", ""));
if (result.startsWith("/")) {
result = result.substring(1);
}
return new URL(result);
}