Create class for sulfuras items

Java/src/main/java/com/gildedrose/items/SulfurasItem.java

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+package com.gildedrose.items;
+
+import com.gildedrose.Quality;
+import com.gildedrose.SellIn;
+import lombok.EqualsAndHashCode;
+
+@EqualsAndHashCode(callSuper = true)
+public class SulfurasItem extends GildedRoseItem {
+
+  static final Quality DEFAULT_QUALITY = Quality.create(80);
+
+  public SulfurasItem(SellIn sellIn) {
+    super("Sulfuras", sellIn, DEFAULT_QUALITY, Boolean.FALSE);
+  }
+
+  @Override
+  protected Quality nextQuality(Quality previous) {
+    // being a legendary item, never has to be sold or decreases in Quality
+    return previous.copy();
+  }
+}

Java/src/test/java/com/gildedrose/items/SulfurasItemTest.java

@@ -0,0 +1,22 @@
+package com.gildedrose.items;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.gildedrose.Quality;
+import com.gildedrose.SellIn;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+class SulfurasItemTest {
+  private final SulfurasItem item = new SulfurasItem(SellIn.create(0));
+
+  @Nested
+  class nextQuality {
+    @Test
+    void should_never_update_quality() {
+      Quality nextQuality = item.nextQuality(SulfurasItem.DEFAULT_QUALITY);
+
+      assertThat(nextQuality).isEqualTo(SulfurasItem.DEFAULT_QUALITY);
+    }
+  }
+}