in saml-authentication-server/src/main/java/jetbrains/buildServer/auth/saml/plugin/SamlLoginPageExtension.java [59:66]
public String getLoginUrl() {
String result = WebUtil.combineContextPath(rootUrlHolder.getRootUrl(), SamlPluginConstants.SAML_INITIATE_LOGIN_URL.replace("**", ""));
if (result.startsWith("/")) {
result = result.substring(1);
}
return result;
}