Use the Validator interface when possible for readability

src/main/java/net/minestom/server/command/builder/arguments/ArgumentBoolean.java

@@ -12,7 +12,7 @@ public class ArgumentBoolean extends Argument<Boolean> {
     public static final int NOT_BOOLEAN_ERROR = 1;
 
     public ArgumentBoolean(String id) {
-        super(id, false);
+        super(id);
     }
 
     @Override

src/main/java/net/minestom/server/command/builder/arguments/number/ArgumentNumber.java

@@ -16,7 +16,7 @@ public abstract class ArgumentNumber<T extends Number> extends Argument<T> {
     protected T min, max;
 
     public ArgumentNumber(String id) {
-        super(id, false);
+        super(id);
     }
 
     @NotNull

src/main/java/net/minestom/server/network/ConnectionManager.java

@@ -7,6 +7,7 @@ import net.minestom.server.listener.manager.PacketConsumer;
 import net.minestom.server.network.packet.client.login.LoginStartPacket;
 import net.minestom.server.network.packet.server.play.ChatMessagePacket;
 import net.minestom.server.network.player.PlayerConnection;
+import net.minestom.server.utils.callback.validator.PlayerValidator;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -14,7 +15,6 @@ import java.util.*;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.function.Consumer;
-import java.util.function.Function;
 
 /**
  * Manages the connected clients.
@@ -93,7 +93,7 @@ public final class ConnectionManager {
      * @param jsonMessage the message to send, probably a {@link net.minestom.server.chat.ColoredText} or {@link net.minestom.server.chat.RichMessage}
      * @param condition   the condition to receive the message
      */
-    public void broadcastMessage(@NotNull JsonMessage jsonMessage, @Nullable Function<Player, Boolean> condition) {
+    public void broadcastMessage(@NotNull JsonMessage jsonMessage, @Nullable PlayerValidator condition) {
         final Collection<Player> recipients = getRecipients(condition);
 
         if (!recipients.isEmpty()) {
@@ -117,7 +117,7 @@ public final class ConnectionManager {
         PacketWriterUtils.writeAndSend(recipients, chatMessagePacket);
     }
 
-    private Collection<Player> getRecipients(@Nullable Function<Player, Boolean> condition) {
+    private Collection<Player> getRecipients(@Nullable PlayerValidator condition) {
         Collection<Player> recipients;
 
         // Get the recipients
@@ -126,7 +126,7 @@ public final class ConnectionManager {
         } else {
             recipients = new ArrayList<>();
             getOnlinePlayers().forEach(player -> {
-                final boolean result = condition.apply(player);
+                final boolean result = condition.isValid(player);
                 if (result)
                     recipients.add(player);
             });

src/main/java/net/minestom/server/thread/ThreadProvider.java

@@ -6,6 +6,7 @@ import net.minestom.server.instance.Chunk;
 import net.minestom.server.instance.Instance;
 import net.minestom.server.instance.InstanceContainer;
 import net.minestom.server.instance.SharedInstance;
+import net.minestom.server.utils.callback.validator.EntityValidator;
 import net.minestom.server.utils.chunk.ChunkUtils;
 import net.minestom.server.utils.thread.MinestomThread;
 import org.jetbrains.annotations.NotNull;
@@ -16,7 +17,6 @@ import java.util.Set;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Future;
 import java.util.function.Consumer;
-import java.util.function.Function;
 
 /**
  * Used to link chunks into multiple groups.
@@ -216,12 +216,12 @@ public abstract class ThreadProvider {
      * @param condition the condition which confirm if the update happens or not
      */
     protected void conditionalEntityUpdate(@NotNull Instance instance, @NotNull Chunk chunk, long time,
-                                           @Nullable Function<Entity, Boolean> condition) {
+                                           @Nullable EntityValidator condition) {
         final Set<Entity> entities = instance.getChunkEntities(chunk);
 
         if (!entities.isEmpty()) {
             for (Entity entity : entities) {
-                if (condition != null && !condition.apply(entity))
+                if (condition != null && !condition.isValid(entity))
                     continue;
                 entity.tick(time);
             }

src/main/java/net/minestom/server/utils/callback/validator/EntityValidator.java

@@ -0,0 +1,7 @@
+package net.minestom.server.utils.callback.validator;
+
+import net.minestom.server.entity.Entity;
+
+@FunctionalInterface
+public interface EntityValidator extends Validator<Entity> {
+}

src/main/java/net/minestom/server/utils/callback/validator/PlayerValidator.java

@@ -0,0 +1,7 @@
+package net.minestom.server.utils.callback.validator;
+
+import net.minestom.server.entity.Player;
+
+@FunctionalInterface
+public interface PlayerValidator extends Validator<Player> {
+}