provides default implementation for method updateItemSellIn()

Java/src/main/java/com/gildedrose/item/AgedBrie.java

@@ -6,11 +6,6 @@ class AgedBrie extends CustomisedItem {
         super(item);
     }
 
-    @Override
-    int updatedItemSellIn() {
-        return item.sellIn -= 1;
-    }
-
     @Override
     int updatedItemQuality() {
         return item.quality += 1;

Java/src/main/java/com/gildedrose/item/BackstagePassesItem.java

@@ -6,11 +6,6 @@ class BackstagePassesItem extends CustomisedItem {
         super(item);
     }
 
-    @Override
-    int updatedItemSellIn() {
-        return item.sellIn -= 1;
-    }
-
     @Override
     int updatedItemQuality() {
         if (sellByDayValueIsOver(10)) {

Java/src/main/java/com/gildedrose/item/ConjuredItem.java

@@ -6,11 +6,6 @@ class ConjuredItem extends CustomisedItem {
         super(item);
     }
 
-    @Override
-    int updatedItemSellIn() {
-        return item.sellIn -= 1;
-    }
-
     @Override
     int updatedItemQuality() {
         if (sellByDayValueIsOverZero()) {

Java/src/main/java/com/gildedrose/item/CustomisedItem.java

@@ -19,7 +19,9 @@ public abstract class CustomisedItem {
         }
     }
 
-    abstract int updatedItemSellIn();
+    int updatedItemSellIn() {
+        return item.sellIn -= 1;
+    }
 
     abstract int updatedItemQuality();
 

Java/src/main/java/com/gildedrose/item/StandardItem.java

@@ -6,11 +6,6 @@ class StandardItem extends CustomisedItem {
         super(item);
     }
 
-    @Override
-    int updatedItemSellIn() {
-        return item.sellIn -= 1;
-    }
-
     @Override
     int updatedItemQuality() {
         if (sellByDayValueIsOverZero()) {