Modified Java code to allow passing Null as valid input for desired and reported properties (#216)

* Modified Java code to allow passing Null as valid input for desired and reported properties
* Renamed variableIsNullValid to variableIsNullable for better readability. Added setting IsNullable to parsing from payload
* Removed legacy leftovers from a previous test attempt at passing Null

Author: TwistedTwigleg

samples/Shadow/src/main/java/shadow/ShadowSample.java

@@ -159,8 +159,23 @@ static void onShadowDeltaUpdated(ShadowDeltaUpdatedEvent response) {
     }
 
     static void onUpdateShadowAccepted(UpdateShadowResponse response) {
-        String value = response.state.reported.get(SHADOW_PROPERTY).toString();
-        System.out.println("Shadow updated, value is " + value);
+        if (response.state.reported != null) {
+            if (response.state.reported.containsKey(SHADOW_PROPERTY)) {
+                String value = response.state.reported.get(SHADOW_PROPERTY).toString();
+                System.out.println("Shadow updated, value is " + value);
+            }
+            else {
+                System.out.println("Shadow updated, value is Null");
+            }
+        }
+        else {
+            if (response.state.reportedIsNullable == true) {
+                System.out.println("Shadow updated, reported and desired is null");
+            }
+            else {
+                System.out.println("Shadow update, data cleared");
+            }
+        }
         gotResponse.complete(null);
     }
 
@@ -170,11 +185,13 @@ static void onUpdateShadowRejected(ErrorResponse response) {
     }
 
     static CompletableFuture<Void> changeShadowValue(String value) {
-        if (localValue.equals(value)) {
-            System.out.println("Local value is already " + value);
-            CompletableFuture<Void> result = new CompletableFuture<>();
-            result.complete(null);
-            return result;
+        if (localValue != null) {
+            if (localValue.equals(value)) {
+                System.out.println("Local value is already " + value);
+                CompletableFuture<Void> result = new CompletableFuture<>();
+                result.complete(null);
+                return result;
+            }
         }
 
         System.out.println("Changed local value to " + value);
@@ -186,13 +203,36 @@ static CompletableFuture<Void> changeShadowValue(String value) {
         UpdateShadowRequest request = new UpdateShadowRequest();
         request.thingName = thingName;
         request.state = new ShadowState();
+        
         request.state.reported = new HashMap<String, Object>() {{
            put(SHADOW_PROPERTY, value);
         }};
         request.state.desired = new HashMap<String, Object>() {{
             put(SHADOW_PROPERTY, value);
         }};
 
+        if (value.compareToIgnoreCase("clear_shadow") == 0) {
+            request.state.desiredIsNullable = true;
+            request.state.reportedIsNullable = true;
+            request.state.desired = null;
+            request.state.reported = null;
+        }
+        else if (value.compareToIgnoreCase("null") == 0) {
+            // A bit of a hack - we have to set reportedNullIsValid OR desiredNullIsValid
+            // so the JSON formatter will allow null , otherwise null will always be
+            // be converted to "null"
+            // As long as we're passing a Hashmap that is NOT assigned to null, it will not
+            // clear the data - so we pass an empty HashMap to avoid clearing data we want to keep
+            request.state.desiredIsNullable = true;
+            request.state.reportedIsNullable = false;
+
+            // We will only clear desired, so we need to pass an empty HashMap for reported
+            request.state.reported = new HashMap<String, Object>() {{}};
+             request.state.desired = new HashMap<String, Object>() {{
+                 put(SHADOW_PROPERTY, null);
+             }};
+        }
+
         // Publish the request
         return shadow.PublishUpdateShadow(request, QualityOfService.AT_LEAST_ONCE).thenRun(() -> {
             System.out.println("Update request published");

sdk/pom.xml

@@ -42,7 +42,7 @@
     <dependency>
       <groupId>software.amazon.awssdk.crt</groupId>
       <artifactId>aws-crt</artifactId>
-      <version>0.15.9</version>
+      <version>0.15.17</version>
     </dependency>
     <dependency>
       <groupId>org.slf4j</groupId>

sdk/src/main/java/software/amazon/awssdk/iot/ShadowStateFactory.java

@@ -0,0 +1,62 @@
+package software.amazon.awssdk.iot;
+
+import software.amazon.awssdk.iot.iotshadow.model.ShadowState;
+
+import java.io.IOException;
+import java.util.HashMap;
+
+import com.google.gson.Gson;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+
+public class ShadowStateFactory implements TypeAdapterFactory {
+
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+
+        Class<T> rawType = (Class<T>)type.getRawType();
+        if (rawType != ShadowState.class) {
+            return null;
+        }
+
+        final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);
+
+        return new TypeAdapter<T>() {
+            public void write(JsonWriter out, T shadowValue) throws IOException {
+                // Are null values allowed?
+                ShadowState shadow = (ShadowState)shadowValue;
+                if (shadow.desiredIsNullable == true || shadow.reportedIsNullable == true) {
+                    out.setSerializeNulls(true);
+                }
+                // If a property is null but null is not valid for it, then just send an empty HashMap
+                if (shadow.desired == null && shadow.desiredIsNullable == false) {
+                    shadow.desired = new HashMap<String, Object>();
+                }
+                if (shadow.reported == null && shadow.reportedIsNullable == false) {
+                    shadow.reported = new HashMap<String, Object>();
+                }
+                delegate.write(out, shadowValue);
+                if (shadow.desiredIsNullable == true || shadow.reportedIsNullable == true) {
+                    out.setSerializeNulls(false);
+                }
+            }
+            public T read(JsonReader in) throws IOException {
+                T returnType = delegate.read(in);
+
+                // Set <Name>IsNullable if the field we get is null
+                ShadowState shadow = (ShadowState)returnType;
+                if (shadow.desired == null) {
+                    shadow.desiredIsNullable = true;
+                }
+                if (shadow.reported == null) {
+                    shadow.reportedIsNullable = true;
+                }
+                returnType = (T)shadow;
+
+                return returnType;
+            }
+        };
+    }
+}

sdk/src/main/java/software/amazon/awssdk/iot/iotshadow/IotShadowClient.java

@@ -45,6 +45,8 @@
 import software.amazon.awssdk.iot.Timestamp;
 import software.amazon.awssdk.iot.EnumSerializer;
 
+import software.amazon.awssdk.iot.ShadowStateFactory;
+
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 
@@ -77,6 +79,8 @@ private Gson getGson() {
     }
 
     private void addTypeAdapters(GsonBuilder gson) {
+        ShadowStateFactory shadowStateFactory = new ShadowStateFactory();
+        gson.registerTypeAdapterFactory(shadowStateFactory);
     }
 
     /**

sdk/src/main/java/software/amazon/awssdk/iot/iotshadow/model/DeleteNamedShadowRequest.java

@@ -20,16 +20,19 @@ public class DeleteNamedShadowRequest {
      */
     public String clientToken;
 
+
     /**
      * Name of the shadow to delete.
      *
      */
     public String shadowName;
 
+
     /**
      * AWS IoT thing to delete a named shadow from.
      *
      */
     public String thingName;
 
+
 }

sdk/src/main/java/software/amazon/awssdk/iot/iotshadow/model/DeleteNamedShadowSubscriptionRequest.java

@@ -20,10 +20,12 @@ public class DeleteNamedShadowSubscriptionRequest {
      */
     public String thingName;
 
+
     /**
      * Name of the shadow to subscribe to DeleteNamedShadow operations for.
      *
      */
     public String shadowName;
 
+
 }

sdk/src/main/java/software/amazon/awssdk/iot/iotshadow/model/DeleteShadowRequest.java

@@ -20,10 +20,12 @@ public class DeleteShadowRequest {
      */
     public String thingName;
 
+
     /**
      * Optional. A client token used to correlate requests and responses. Enter an arbitrary value here and it is reflected in the response.
      *
      */
     public String clientToken;
 
+
 }

sdk/src/main/java/software/amazon/awssdk/iot/iotshadow/model/DeleteShadowResponse.java

@@ -21,16 +21,19 @@ public class DeleteShadowResponse {
      */
     public Integer version;
 
+
     /**
      * A client token used to correlate requests and responses.
      *
      */
     public String clientToken;
 
+
     /**
      * The time the response was generated by AWS IoT.
      *
      */
     public Timestamp timestamp;
 
+
 }

sdk/src/main/java/software/amazon/awssdk/iot/iotshadow/model/DeleteShadowSubscriptionRequest.java

@@ -20,4 +20,5 @@ public class DeleteShadowSubscriptionRequest {
      */
     public String thingName;
 
+
 }

sdk/src/main/java/software/amazon/awssdk/iot/iotshadow/model/ErrorResponse.java

@@ -21,22 +21,26 @@ public class ErrorResponse {
      */
     public Timestamp timestamp;
 
+
     /**
      * A text message that provides additional information.
      *
      */
     public String message;
 
+
     /**
      * Opaque request-response correlation data.  Present only if a client token was used in the request.
      *
      */
     public String clientToken;
 
+
     /**
      * An HTTP response code that indicates the type of error.
      *
      */
     public Integer code;
 
+
 }