Some small optimizations (#4305)

some improvements to itemmeta calls and misc changes

src/main/java/com/gmail/nossr50/util/ItemUtils.java

@@ -18,6 +18,10 @@ import org.jetbrains.annotations.NotNull;
 import java.util.List;
 
 public final class ItemUtils {
+    /**
+     * This is a static utility class, therefore we don't want any instances of
+     * this class. Making the constructor private prevents accidents like that.
+     */
     private ItemUtils() {}
 
     /**