Add EntityToggleSwimEvent and isSwimming / setSwimming API

By: md_5 <git@md-5.net>

paper-api/src/main/java/org/bukkit/event/entity/EntityToggleSwimEvent.java

@@ -0,0 +1,43 @@
+package org.bukkit.event.entity;
+
+import org.bukkit.entity.LivingEntity;
+import org.bukkit.event.Cancellable;
+import org.bukkit.event.HandlerList;
+
+/**
+ * Sent when an entity's swimming status is toggled.
+ */
+public class EntityToggleSwimEvent extends EntityEvent implements Cancellable {
+    private static final HandlerList handlers = new HandlerList();
+
+    private boolean cancel = false;
+    private final boolean isSwimming;
+
+    public EntityToggleSwimEvent(LivingEntity who, final boolean isSwimming) {
+        super(who);
+        this.isSwimming = isSwimming;
+    }
+
+    @Override
+    public boolean isCancelled() {
+        return cancel;
+    }
+
+    @Override
+    public void setCancelled(boolean cancel) {
+        this.cancel = cancel;
+    }
+
+    public boolean isSwimming() {
+        return isSwimming;
+    }
+
+    @Override
+    public HandlerList getHandlers() {
+        return handlers;
+    }
+
+    public static HandlerList getHandlerList() {
+        return handlers;
+    }
+}