v4.5.1: Serializing null values correctly & bumping gson@2.8.9 (#32)

## v.4.5.1: Serializing null values correctly & bumping gson@2.8.9

### Serializing `null` values in attribute objects correctly 

When sending integration requests, allowing to remove a value for a key by serializing nulls properly.
As explained at the bottom of [this section](https://docs.talon.one/docs/dev/concepts/attributes/#setting-attributes) in our [documentation website](https://docs.talon.one/)

closes #31 

### Upgrade gson dependency

Bump the gson dependency a few minor versions up, to 2.8.9 to resolve a potential security issue with the current version (2.8.6)

closes #30 


## Commit Summary 

* Add custom JsonNullable adapter and attribute class
* Apply the JsonNullable attribute where applicable
* Bump gson to 2.8.9
* Bump version to 4.5.1

Author: altJake

README.md

@@ -53,7 +53,7 @@ Add this dependency to your project's POM:
 <dependency>
   <groupId>one.talon</groupId>
   <artifactId>talon-one-client</artifactId>
-  <version>4.5.0</version>
+  <version>4.5.1</version>
   <scope>compile</scope>
 </dependency>
 ```
@@ -63,7 +63,7 @@ Add this dependency to your project's POM:
 Add this dependency to your project's build file:
 
 ```groovy
-compile "one.talon:talon-one-client:4.5.0"
+compile "one.talon:talon-one-client:4.5.1"
 ```
 
 ### Others
@@ -76,49 +76,134 @@ mvn clean package
 
 Then manually install the following JARs:
 
-* `target/talon-one-client-4.5.0.jar`
+* `target/talon-one-client-4.5.1.jar`
 * `target/lib/*.jar`
 
 ## Getting Started
 
 Please follow the [installation](#installation) instruction and execute the following Java code:
 
+### Integration API
+
+**Note:** The Integration API's V1 `Update customer session` and `Update customer profile` endpoints are now deprecated. Use their V2 instead. See [Migrating to V2](https://docs.talon.one/docs/dev/tutorials/migrating-to-v2) for more information.
+
 ```java
+package com.example.consumer;
+
+import com.google.gson.Gson;
 
-// Import classes:
 import one.talon.ApiClient;
-import one.talon.ApiException;
-import one.talon.Configuration;
-import one.talon.auth.*;
-import one.talon.models.*;
 import one.talon.api.IntegrationApi;
-
-public class Example {
-  public static void main(String[] args) {
-    ApiClient defaultClient = Configuration.getDefaultApiClient();
-    defaultClient.setBasePath("http://localhost");
-    
-    // Configure API key authorization: api_key_v1
-    ApiKeyAuth api_key_v1 = (ApiKeyAuth) defaultClient.getAuthentication("api_key_v1");
-    api_key_v1.setApiKey("YOUR API KEY");
-    // Uncomment the following line to set a prefix for the API key, e.g. "Token" (defaults to null)
-    //api_key_v1.setApiKeyPrefix("Token");
-
-    IntegrationApi apiInstance = new IntegrationApi(defaultClient);
-    NewAudience body = new NewAudience(); // NewAudience | 
-    try {
-      Audience result = apiInstance.createAudienceV2(body);
-      System.out.println(result);
-    } catch (ApiException e) {
-      System.err.println("Exception when calling IntegrationApi#createAudienceV2");
-      System.err.println("Status code: " + e.getCode());
-      System.err.println("Reason: " + e.getResponseBody());
-      System.err.println("Response headers: " + e.getResponseHeaders());
-      e.printStackTrace();
+import one.talon.api.ManagementApi;
+import one.talon.model.*;
+
+public class TalonApiTest {
+    public static void main(String[] args) {
+        Gson gson = new Gson();
+        IntegrationApi iApi = new IntegrationApi(new ApiClient("api_key_v1"));
+
+        // Setup: basePath
+        iApi.getApiClient().setBasePath("https://mycompany.talon.one");
+        // Setup: when using 'api_key_v1', set apiKey & apiKeyPrefix must be provided
+        iApi.getApiClient().setApiKeyPrefix("ApiKey-v1");
+        iApi.getApiClient().setApiKey("dbc644d33aa74d582bd9479c59e16f970fe13bf34a208c39d6c7fa7586968468");
+
+        try {
+          // Creating a cart item object
+            CartItem cartItem = new CartItem();
+            cartItem.setName("Hawaiian Pizza");
+            cartItem.setSku("pizza-x");
+            cartItem.setQuantity(1);
+            cartItem.setPrice(new java.math.BigDecimal("5.5"));
+
+            // Creating a customer session of V2
+            NewCustomerSessionV2 customerSession = new NewCustomerSessionV2();
+            customerSession.setProfileId("Cool_Dude");
+            customerSession.addCouponCodesItem("Cool-Summer!");
+            customerSession.addCartItemsItem(cartItem);
+
+            // Initiating integration request wrapping the customer session update
+            IntegrationRequest request = new IntegrationRequest()
+                .customerSession(customerSession)
+                // Optional parameter of requested information to be present on the response related to the customer session update
+                .responseContent(Arrays.asList(
+                    IntegrationRequest.ResponseContentEnum.CUSTOMERSESSION,
+                    IntegrationRequest.ResponseContentEnum.CUSTOMERPROFILE
+                ));
+
+            // Flag to communicate whether the request is a "dry run"
+            Boolean dryRun = false;
+
+            // Create/update a customer session using `updateCustomerSessionV2` function
+            IntegrationStateV2 is = iApi.updateCustomerSessionV2("deetdoot", request, dryRun);
+            System.out.println(is.toString());
+
+            // Parsing the returned effects list, please consult https://developers.talon.one/Integration-API/handling-effects-v2 for the full list of effects and their corresponding properties
+            for (Effect eff : is.getEffects()) {
+                if (eff.getEffectType().equals("addLoyaltyPoints")) {
+                    // Typecasting according to the specific effect type
+                    AddLoyaltyPointsEffectProps props = gson.fromJson(
+                        gson.toJson(eff.getProps()),
+                        AddLoyaltyPointsEffectProps.class
+                    );
+                    // Access the specific effect's properties
+                    System.out.println(props.getName());
+                    System.out.println(props.getProgramId());
+                    System.out.println(props.getValue());
+                }
+                if (eff.getEffectType().equals("acceptCoupon")) {
+                    // Typecasting according to the specific effect type
+                    AcceptCouponEffectProps props = gson.fromJson(
+                      gson.toJson(eff.getProps()),
+                      AcceptCouponEffectProps.class
+                    );
+                    // work with AcceptCouponEffectProps' properties
+                    // ...
+                }
+            }
+        } catch (Exception e) {
+            System.out.println(e);
+        }
     }
-  }
 }
+```
+
+### Management API
 
+```java
+package com.example.consumer;
+
+import one.talon.ApiClient;
+import one.talon.api.IntegrationApi;
+import one.talon.api.ManagementApi;
+import one.talon.model.*;
+
+public class TalonApiTest {
+    public static void main(String[] args) {
+        // Management API example to load application with id 7
+        ManagementApi mApi = new ManagementApi(new ApiClient("manager_auth"));
+
+        // Setup: basePath and bearer prefix
+        mApi.getApiClient().setBasePath("https://mycompany.talon.one");
+        mApi.getApiClient().setApiKeyPrefix("Bearer");
+
+        LoginParams lp = new LoginParams();
+        lp.setEmail("admin@talon.one");
+        lp.setPassword("yourpassword");
+
+        try {
+            // Acquire session token
+            Session s = mApi.createSession(lp);
+            mApi.getApiClient().setApiKey(s.getToken());
+
+            // Calling `getApplication` function with the desired id (7)
+            Application application = mApi.getApplication(7);
+            System.out.println(application.toString());
+        } catch (Exception e) {
+            System.out.println(e);
+        }
+    }
+}
 ```
 
 ## Documentation for API Endpoints

build.gradle

@@ -3,7 +3,7 @@ apply plugin: 'eclipse'
 apply plugin: 'java'
 
 group = 'one.talon'
-version = '4.5.0'
+version = '4.5.1'
 
 buildscript {
     repositories {

build.sbt

@@ -2,7 +2,7 @@ lazy val root = (project in file(".")).
   settings(
     organization := "one.talon",
     name := "talon-one-client",
-    version := "4.5.0",
+    version := "4.5.1",
     scalaVersion := "2.11.4",
     scalacOptions ++= Seq("-feature"),
     javacOptions in compile ++= Seq("-Xlint:deprecation"),

pom.xml

@@ -5,7 +5,7 @@
     <artifactId>talon-one-client</artifactId>
     <packaging>jar</packaging>
     <name>talon-one-client</name>
-    <version>4.5.0</version>
+    <version>4.5.1</version>
     <url>https://github.com/talon-one/maven-artefacts</url>
     <description>Talon.One unified JAVA SDK. It allows for programmatic access to the integration and management API with their respective authentication strategies</description>
     <scm>
@@ -271,7 +271,7 @@
         <gson-fire-version>1.8.4</gson-fire-version>
         <swagger-core-version>1.5.24</swagger-core-version>
         <okhttp-version>3.14.7</okhttp-version>
-        <gson-version>2.8.6</gson-version>
+        <gson-version>2.8.9</gson-version>
         <commons-lang3-version>3.10</commons-lang3-version>
         <threetenbp-version>1.4.3</threetenbp-version>
         <javax-annotation-version>1.3.2</javax-annotation-version>

src/main/java/one/talon/ApiClient.java

@@ -127,7 +127,7 @@ private void init() {
         json = new JSON();
 
         // Set default User-Agent.
-        setUserAgent("OpenAPI-Generator/4.5.0/java");
+        setUserAgent("OpenAPI-Generator/4.5.1/java");
 
         authentications = new HashMap<String, Authentication>();
     }

src/main/java/one/talon/custom/JsonNullable.java

@@ -0,0 +1,11 @@
+package one.talon.custom;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.FIELD)
+public @interface JsonNullable {
+}

src/main/java/one/talon/custom/NullableAdapterFactory.java

@@ -0,0 +1,123 @@
+package one.talon.custom;
+
+import com.google.gson.*;
+import com.google.gson.annotations.SerializedName;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+
+import javax.annotation.Nullable;
+import java.io.IOException;
+import java.lang.reflect.Field;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+public class NullableAdapterFactory implements TypeAdapterFactory {
+
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+        Field[] declaredFields = type.getRawType().getDeclaredFields();
+        final List<String> nullableFieldNames = new ArrayList<>();
+        final List<String> nonNullableFieldNames = new ArrayList<>();
+        for (Field declaredField : declaredFields) {
+            if (declaredField.isAnnotationPresent(JsonNullable.class)) {
+                if (declaredField.getAnnotation(SerializedName.class) != null) {
+                    nullableFieldNames.add(declaredField.getAnnotation(SerializedName.class).value());
+                } else {
+                    nullableFieldNames.add(declaredField.getName());
+                }
+            } else {
+                if (declaredField.getAnnotation(SerializedName.class) != null) {
+                    nonNullableFieldNames.add(declaredField.getAnnotation(SerializedName.class).value());
+                } else {
+                    nonNullableFieldNames.add(declaredField.getName());
+                }
+            }
+        }
+
+        if (nullableFieldNames.size() == 0) {
+            return null;
+        }
+        final TypeAdapter<T> delegateAdapter = gson.getDelegateAdapter(NullableAdapterFactory.this, type);
+        final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
+
+        return new TypeAdapter<T>() {
+            @Override
+            public void write(JsonWriter out, T value) throws IOException {
+                JsonObject jsonObject = delegateAdapter.toJsonTree(value).getAsJsonObject();
+                for (String name: nonNullableFieldNames) {
+                    if (jsonObject.has(name)) {
+                       JsonElement element =jsonObject.get(name);
+                       if(element==null || element instanceof JsonNull){
+                           jsonObject.remove(name);
+                       }
+                       if(element==null || element instanceof JsonObject){
+                           removeNullsFrom((JsonObject) element);
+                       }
+                        if(element instanceof JsonArray){
+                            removeNullsFrom((JsonArray) element);
+                        }
+                    }
+                }
+
+                // remove null-valued nullablae fields; preventing them getting output if they do not have _any value_
+                for (String name: nullableFieldNames) {
+                    if (jsonObject.has(name)) {
+                       JsonElement element =jsonObject.get(name);
+                       if(element==null || element instanceof JsonNull){
+                           jsonObject.remove(name);
+                       }
+                    }
+                }
+
+                boolean originalSerializeNulls = out.getSerializeNulls();
+                out.setSerializeNulls(true);
+                elementAdapter.write(out, jsonObject);
+                out.setSerializeNulls(originalSerializeNulls);
+            }
+
+            @Override
+            public T read(JsonReader in) throws IOException {
+                return delegateAdapter.read(in);
+            }
+
+            public void removeNullsFrom(@Nullable JsonObject object) {
+                if (object != null) {
+                    Iterator<String> iterator = object.keySet().iterator();
+                    while (iterator.hasNext()) {
+                        String key = iterator.next();
+                        Object o = object.get(key);
+                        if (o == null || o instanceof JsonNull) {
+                            iterator.remove();
+                        }
+                        else if(o instanceof JsonObject){
+                            removeNullsFrom((JsonObject) o);
+                        }
+                        else if(o instanceof JsonArray){
+                            removeNullsFrom((JsonArray) o);
+                        }
+                    }
+                }
+            }
+
+            public void removeNullsFrom(@Nullable JsonArray array)  {
+                if (array != null) {
+                    for (int i = 0; i < array.size(); i++) {
+                        Object o = array.get(i);
+                        if (o == null || o instanceof JsonNull) {
+                            array.remove(i);
+                        } else if(o instanceof JsonObject){
+                            removeNullsFrom((JsonObject) o);
+                        }
+                        else if(o instanceof JsonArray){
+                            removeNullsFrom((JsonArray) o);
+                        }
+                    }
+                }
+            }
+
+
+        };
+    }
+}

src/main/java/one/talon/model/CartItem.java

@@ -28,11 +28,13 @@
 import java.util.List;
 import java.util.Map;
 import one.talon.model.AdditionalCost;
+import one.talon.custom.JsonNullable;
+import one.talon.custom.NullableAdapterFactory;
 
 /**
  * CartItem
  */
-
+@JsonAdapter(NullableAdapterFactory.class)
 public class CartItem {
   public static final String SERIALIZED_NAME_NAME = "name";
   @SerializedName(SERIALIZED_NAME_NAME)
@@ -84,6 +86,8 @@ public class CartItem {
 
   public static final String SERIALIZED_NAME_ATTRIBUTES = "attributes";
   @SerializedName(SERIALIZED_NAME_ATTRIBUTES)
+  /*allow Serializing null for this field */
+  @JsonNullable
   private Object attributes;
 
   public static final String SERIALIZED_NAME_ADDITIONAL_COSTS = "additionalCosts";