Resolve matomo-org#13. ClassCastException when trying to send PiwikRequest with EcommeceItem

Author: bcsorba

src/main/java/org/piwik/java/tracking/EcommerceItem.java

@@ -7,6 +7,7 @@
 package org.piwik.java.tracking;
 
 import javax.json.Json;
+import javax.json.JsonArray;
 import javax.json.JsonArrayBuilder;
 import javax.json.JsonValue;
 
@@ -129,18 +130,25 @@ public ValueType getValueType(){
     }
 
     /**
-     * Returns the value of this EcommerceItem as a JSON Object string.
-     * @return JSON object string
+     * Returns the value of this EcommerceItem as a JSON Array string.
+     * @return this as a JSON array string
      */
     @Override
     public String toString(){
+        return toJsonArray().toString();
+    }
+    /**
+     * Returns the value of this EcommerceItem as a JsonArray.
+     * @return this as a JsonArray
+     */
+    protected JsonArray toJsonArray(){
         JsonArrayBuilder ab = Json.createArrayBuilder();
         ab.add(sku);
         ab.add(name);
         ab.add(category);
         ab.add(price);
         ab.add(quantity);
 
-        return ab.build().toString();
+        return ab.build();        
     }
 }

src/main/java/org/piwik/java/tracking/PiwikJsonArray.java

@@ -55,7 +55,13 @@ public String toString(){
         JsonArrayBuilder ab = Json.createArrayBuilder();
 
         for (int x = 0; x < list.size(); ++x){
-            ab.add(list.get(x));
+            JsonValue value = list.get(x);
+            if (value instanceof EcommerceItem){
+                ab.add(((EcommerceItem)value).toJsonArray());
+            }
+            else{
+                ab.add(value);
+            }
         }
 
         return ab.build().toString();

src/test/java/org/piwik/java/tracking/PiwikJsonArrayTest.java

@@ -63,9 +63,10 @@ public void testAddGetSet(){
     @Test
     public void testToString(){
         array.add(JsonValue.TRUE);
+        array.add(new EcommerceItem("a", "b", "c", 1.0, 2));
         array.add(JsonValue.FALSE);
 
-        assertEquals("[true,false]", array.toString());
+        assertEquals("[true,[\"a\",\"b\",\"c\",1.0,2],false]", array.toString());
     }
 
 }