Source:
public Mono<AccessToken> authenticateToManagedIdentityEndpoint(String identityEndpoint, String identityHeader, String msiEndpoint, String msiSecret, TokenRequestContext request) { return Mono.fromCallable(() -> { String endpoint; String headerValue; String endpointVersion; if (identityEndpoint != null) { endpoint = identityEndpoint; headerValue = identityHeader; endpointVersion = IDENTITY_ENDPOINT_VERSION; } else { endpoint = msiEndpoint; headerValue = msiSecret; endpointVersion = MSI_ENDPOINT_VERSION; } String resource = ScopeUtil.scopesToResource(request.getScopes()); HttpURLConnection connection = null; StringBuilder payload = new StringBuilder(); payload.append("resource="); payload.append(URLEncoder.encode(resource, "UTF-8")); payload.append("&api-version="); payload.append(URLEncoder.encode(endpointVersion, "UTF-8")); if (clientId != null) { payload.append("&clientid="); payload.append(URLEncoder.encode(clientId, "UTF-8")); } try { URL url = new URL(String.format("%s?%s", endpoint, payload)); connection = (HttpURLConnection) url.openConnection(); connection.setRequestMethod("GET"); if (headerValue != null) { if (endpointVersion.equals(IDENTITY_ENDPOINT_VERSION)) { connection.setRequestProperty("X-IDENTITY-HEADER", headerValue); } else { connection.setRequestProperty("Secret", headerValue); } } connection.setRequestProperty("Metadata", "true"); connection.connect(); Scanner s = new Scanner(connection.getInputStream(), StandardCharsets.UTF_8.name()) .useDelimiter("\\A"); String result = s.hasNext() ? s.next() : ""; return SERIALIZER_ADAPTER.deserialize(result, MSIToken.class, SerializerEncoding.JSON); } finally { if (connection != null) { connection.disconnect(); } } }); }

Target:
public Mono<AccessToken> authenticateToManagedIdentityEndpoint(String identityEndpoint, String identityHeader, String msiEndpoint, String msiSecret, TokenRequestContext request) { return Mono.fromCallable(() -> { String endpoint; String headerValue; String endpointVersion; if (identityEndpoint != null) { endpoint = identityEndpoint; headerValue = identityHeader; endpointVersion = IDENTITY_ENDPOINT_VERSION; } else { endpoint = msiEndpoint; headerValue = msiSecret; endpointVersion = MSI_ENDPOINT_VERSION; } String resource = ScopeUtil.scopesToResource(request.getScopes()); HttpURLConnection connection = null; StringBuilder payload = new StringBuilder(); payload.append("resource="); payload.append(URLEncoder.encode(resource, "UTF-8")); payload.append("&api-version="); payload.append(URLEncoder.encode(endpointVersion, "UTF-8")); if (clientId != null) { if (endpointVersion.equals(IDENTITY_ENDPOINT_VERSION)) { payload.append("&client_id="); } else { payload.append("&clientid="); } payload.append(URLEncoder.encode(clientId, "UTF-8")); } try { URL url = new URL(String.format("%s?%s", endpoint, payload)); connection = (HttpURLConnection) url.openConnection(); connection.setRequestMethod("GET"); if (headerValue != null) { if (endpointVersion.equals(IDENTITY_ENDPOINT_VERSION)) { connection.setRequestProperty("X-IDENTITY-HEADER", headerValue); } else { connection.setRequestProperty("Secret", headerValue); } } connection.setRequestProperty("Metadata", "true"); connection.connect(); Scanner s = new Scanner(connection.getInputStream(), StandardCharsets.UTF_8.name()) .useDelimiter("\\A"); String result = s.hasNext() ? s.next() : ""; return SERIALIZER_ADAPTER.deserialize(result, MSIToken.class, SerializerEncoding.JSON); } finally { if (connection != null) { connection.disconnect(); } } }); }