Improve JsonHelper method

Author: Avery-Dunn

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/AadInstanceDiscoveryProvider.java

@@ -121,7 +121,7 @@ static Set<String> getAliases(String host) {
     static AadInstanceDiscoveryResponse parseInstanceDiscoveryMetadata(String instanceDiscoveryJson) {
 
         try {
-            return JsonHelper.convertJsonStringToJsonSerializableObject(instanceDiscoveryJson, AadInstanceDiscoveryResponse.class);
+            return JsonHelper.convertJsonStringToJsonSerializableObject(instanceDiscoveryJson, AadInstanceDiscoveryResponse::fromJson);
         } catch (Exception ex) {
             throw new MsalClientException("Error parsing instance discovery response. Data must be " +
                     "in valid JSON format. For more information, see https://aka.ms/msal4j-instance-discovery",
@@ -233,7 +233,7 @@ static AadInstanceDiscoveryResponse sendInstanceDiscoveryRequest(URL authorityUr
 
         IHttpResponse httpResponse = executeRequest(instanceDiscoveryRequestUrl, msalRequest.headers().getReadonlyHeaderMap(), msalRequest, serviceBundle);
 
-        AadInstanceDiscoveryResponse response = JsonHelper.convertJsonStringToJsonSerializableObject(httpResponse.body(), AadInstanceDiscoveryResponse.class);
+        AadInstanceDiscoveryResponse response = JsonHelper.convertJsonStringToJsonSerializableObject(httpResponse.body(), AadInstanceDiscoveryResponse::fromJson);
 
         if (httpResponse.statusCode() != HttpHelper.HTTP_STATUS_200) {
             if (httpResponse.statusCode() == HttpHelper.HTTP_STATUS_400 && response.error().equals("invalid_instance")) {

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/AbstractManagedIdentitySource.java

@@ -101,7 +101,7 @@ public ManagedIdentityResponse handleResponse(
 
     protected ManagedIdentityResponse getSuccessfulResponse(IHttpResponse response) {
 
-        ManagedIdentityResponse managedIdentityResponse = JsonHelper.convertJsonStringToJsonSerializableObject(response.body(), ManagedIdentityResponse.class);
+        ManagedIdentityResponse managedIdentityResponse = JsonHelper.convertJsonStringToJsonSerializableObject(response.body(), ManagedIdentityResponse::fromJson);
 
         if (managedIdentityResponse == null || managedIdentityResponse.getAccessToken() == null
                 || managedIdentityResponse.getAccessToken().isEmpty() || managedIdentityResponse.getExpiresOn() == null

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/JsonHelper.java

@@ -6,6 +6,7 @@
 import com.azure.json.JsonProviders;
 import com.azure.json.JsonReader;
 import com.azure.json.JsonSerializable;
+import com.azure.json.ReadValueCallback;
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.databind.DeserializationFeature;
@@ -40,9 +41,9 @@ static <T> T convertJsonToObject(final String json, final Class<T> tClass) {
     }
 
     //This method is used to convert a JSON string to an object which implements the JsonSerializable interface from com.azure.json
-    static <T extends JsonSerializable<T>> T convertJsonStringToJsonSerializableObject(String jsonResponse, Class<T> tClass) {
+    static <T extends JsonSerializable<T>> T convertJsonStringToJsonSerializableObject(String jsonResponse, ReadValueCallback<JsonReader, T> readFunction) {
         try (JsonReader jsonReader = JsonProviders.createReader(jsonResponse)) {
-            return (T) tClass.getDeclaredMethod("fromJson", JsonReader.class).invoke(null, jsonReader);
+            return readFunction.read(jsonReader);
         } catch (IOException e) {
             throw new MsalClientException(e.getMessage(), AuthenticationErrorCode.INVALID_JSON);
         } catch (Exception e) {

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/OidcDiscoveryProvider.java

@@ -12,7 +12,7 @@ static OidcDiscoveryResponse performOidcDiscovery(OidcAuthority authority, Abstr
 
         IHttpResponse httpResponse = ((HttpHelper)clientApplication.serviceBundle.getHttpHelper()).executeHttpRequest(httpRequest);
 
-        OidcDiscoveryResponse response = JsonHelper.convertJsonStringToJsonSerializableObject(httpResponse.body(), OidcDiscoveryResponse.class);
+        OidcDiscoveryResponse response = JsonHelper.convertJsonStringToJsonSerializableObject(httpResponse.body(), OidcDiscoveryResponse::fromJson);
 
         if (httpResponse.statusCode() != HttpHelper.HTTP_STATUS_200) {
             throw MsalServiceExceptionFactory.fromHttpResponse(httpResponse);

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/UserDiscoveryRequest.java

@@ -33,6 +33,6 @@ static UserDiscoveryResponse execute(
             throw MsalServiceExceptionFactory.fromHttpResponse(response);
         }
 
-        return JsonHelper.convertJsonStringToJsonSerializableObject(response.body(), UserDiscoveryResponse.class);
+        return JsonHelper.convertJsonStringToJsonSerializableObject(response.body(), UserDiscoveryResponse::fromJson);
     }
 }

msal4j-sdk/src/test/java/com/microsoft/aad/msal4j/AadInstanceDiscoveryTest.java

@@ -54,7 +54,7 @@ void aadInstanceDiscoveryTest_NotSetByDeveloper() throws Exception {
                 new RequestContext(app, PublicApi.ACQUIRE_TOKEN_BY_AUTHORIZATION_CODE, parameters));
 
         URL authority = new URL(app.authority());
-        AadInstanceDiscoveryResponse expectedResponse= JsonHelper.convertJsonStringToJsonSerializableObject(instanceDiscoveryValidResponse, AadInstanceDiscoveryResponse.class);
+        AadInstanceDiscoveryResponse expectedResponse= JsonHelper.convertJsonStringToJsonSerializableObject(instanceDiscoveryValidResponse, AadInstanceDiscoveryResponse::fromJson);
 
         try (MockedStatic<AadInstanceDiscoveryProvider> mockedInstanceDiscoveryProvider = mockStatic(AadInstanceDiscoveryProvider.class, CALLS_REAL_METHODS)) {