Fix ExprBookAuthors performance Java 17 (#7023)

* Fix ExprBookAuthors performance Java 17

* Update src/main/java/ch/njol/skript/expressions/ExprBookAuthor.java

Co-authored-by: Moderocky <admin@moderocky.com>

* Update ExprBookAuthor.java

* Update src/main/java/ch/njol/skript/expressions/ExprBookAuthor.java

Co-authored-by: Patrick Miller <apickledwalrus@gmail.com>

* Update src/main/java/ch/njol/skript/expressions/ExprBookAuthor.java

Co-authored-by: sovdee <10354869+sovdeeth@users.noreply.github.com>

---------

Co-authored-by: Moderocky <admin@moderocky.com>
Co-authored-by: Patrick Miller <apickledwalrus@gmail.com>
Co-authored-by: sovdee <10354869+sovdeeth@users.noreply.github.com>

src/main/java/ch/njol/skript/expressions/ExprBookAuthor.java

@@ -1,21 +1,3 @@
-/**
- *   This file is part of Skript.
- *
- *  Skript is free software: you can redistribute it and/or modify
- *  it under the terms of the GNU General Public License as published by
- *  the Free Software Foundation, either version 3 of the License, or
- *  (at your option) any later version.
- *
- *  Skript is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU General Public License for more details.
- *
- *  You should have received a copy of the GNU General Public License
- *  along with Skript.  If not, see <http://www.gnu.org/licenses/>.
- *
- * Copyright Peter Güttinger, SkriptLang team and contributors
- */
 package ch.njol.skript.expressions;
 
 import ch.njol.skript.aliases.ItemType;
@@ -29,63 +11,54 @@
 
 import org.bukkit.event.Event;
 import org.bukkit.inventory.meta.BookMeta;
-import org.bukkit.inventory.meta.ItemMeta;
-import org.eclipse.jdt.annotation.Nullable;
+import org.jetbrains.annotations.Nullable;
 
 @Name("Book Author")
 @Description("The author of a book.")
-@Examples({"on book sign:",
-			"\tmessage \"Book Title: %author of event-item%\""})
+@Examples({
+	"on book sign:",
+		"\tmessage \"Book Title: %author of event-item%\""
+})
 @Since("2.2-dev31")
 public class ExprBookAuthor extends SimplePropertyExpression<ItemType, String> {
-	
+
 	static {
 		register(ExprBookAuthor.class, String.class, "[book] (author|writer|publisher)", "itemtypes");
 	}
-	
+
 	@Nullable
 	@Override
 	public String convert(ItemType item) {
-		ItemMeta meta = item.getItemMeta();
-
-		if (meta instanceof BookMeta)
-			return ((BookMeta) meta).getAuthor();
-
-		return null;
+		return item.getItemMeta() instanceof BookMeta bookMeta ? bookMeta.getAuthor() : null;
 	}
-
-	@Nullable
+
 	@Override
-	public Class<?>[] acceptChange(ChangeMode mode) {
-		if (mode == ChangeMode.SET || mode == ChangeMode.RESET || mode == ChangeMode.DELETE)
-			return CollectionUtils.array(String.class);
-		return null;
+	public Class<?> @Nullable [] acceptChange(ChangeMode mode) {
+		return switch (mode) {
+			case SET, RESET, DELETE -> CollectionUtils.array(String.class);
+			default -> null;
+		};
 	}
-
-	@SuppressWarnings("null")
+
 	@Override
-	public void change(Event e, @Nullable Object[] delta, ChangeMode mode) {
+	public void change(Event event, Object @Nullable [] delta, ChangeMode mode) {
 		String author = delta == null ? null : (String) delta[0];
-
-		for (ItemType item : getExpr().getArray(e)) {
-			ItemMeta meta = item.getItemMeta();
-
-			if (meta instanceof BookMeta) {
-				((BookMeta) meta).setAuthor(author);
-				item.setItemMeta(meta);
+		for (ItemType item : getExpr().getArray(event)) {
+			if (item.getItemMeta() instanceof BookMeta bookMeta) {
+				bookMeta.setAuthor(author);
+				item.setItemMeta(bookMeta);
 			}
 		}
 	}
-	
+
 	@Override
 	public Class<? extends String> getReturnType() {
 		return String.class;
 	}
-	
+
 	@Override
 	protected String getPropertyName() {
 		return "book author";
 	}
-
-}
 
+}