Renamed some stuff, courtesy of sensiolabs.

app/Generator/Chart/PiggyBank/ChartJsPiggyBankChartGenerator.php

@@ -11,7 +11,7 @@ use Illuminate\Support\Collection;
  *
  * @package FireflyIII\Generator\Chart\PiggyBank
  */
-class ChartJsPiggyBankChartGenerator implements PiggyBankChartGenerator
+class ChartJsPiggyBankChartGenerator implements PiggyBankChartGeneratorInterface
 {
 
     /**

app/Generator/Chart/PiggyBank/PiggyBankChartGenerator.php

@@ -1,20 +0,0 @@
-<?php
-
-namespace FireflyIII\Generator\Chart\PiggyBank;
-
-use Illuminate\Support\Collection;
-
-/**
- * Interface PiggyBankChartGenerator
- *
- * @package FireflyIII\Generator\Chart\PiggyBank
- */
-interface PiggyBankChartGenerator
-{
-    /**
-     * @param Collection $set
-     *
-     * @return array
-     */
-    public function history(Collection $set);
-}

app/Generator/Chart/PiggyBank/PiggyBankChartGeneratorInterface.php

@@ -0,0 +1,27 @@
+<?php
+/**
+ * PiggyBankChartGenerator.php
+ * Copyright (C) 2016 Sander Dorigo
+ *
+ * This software may be modified and distributed under the terms
+ * of the MIT license.  See the LICENSE file for details.
+ */
+
+namespace FireflyIII\Generator\Chart\PiggyBank;
+
+use Illuminate\Support\Collection;
+
+/**
+ * Interface PiggyBankChartGeneratorInterface
+ *
+ * @package FireflyIII\Generator\Chart\PiggyBank
+ */
+interface PiggyBankChartGeneratorInterface
+{
+    /**
+     * @param Collection $set
+     *
+     * @return array
+     */
+    public function history(Collection $set);
+}