Add Horse API. Adds BUKKIT-4424

API has been added to interface with Horses and to modify their inventories. A new event, HorseJumpEvent, has been added to be fired whenever a horse jumps.

This commit fixes BUKKIT-4393.

By: h31ix <zero_gravity@outlook.com>

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

@@ -0,0 +1,78 @@
+package org.bukkit.event.entity;
+
+import org.bukkit.entity.Horse;
+import org.bukkit.event.Cancellable;
+import org.bukkit.event.HandlerList;
+
+/**
+ * Called when a horse jumps.
+ */
+public class HorseJumpEvent extends EntityEvent implements Cancellable {
+    private static final HandlerList handlers = new HandlerList();
+    private boolean cancelled;
+    private float power;
+
+    public HorseJumpEvent(final Horse horse, final float power) {
+        super(horse);
+        this.power = power;
+    }
+
+    public boolean isCancelled() {
+        return cancelled;
+    }
+
+    public void setCancelled(boolean cancel) {
+        cancelled = cancel;
+    }
+
+    @Override
+    public Horse getEntity() {
+        return (Horse) entity;
+    }
+
+    /**
+     * Gets the power of the jump.
+     * <p>
+     * Power is a value that defines how much of the horse's jump strength
+     * should be used for the jump. Power is effectively multiplied times
+     * the horse's jump strength to determine how high the jump is;
+     * 0 represents no jump strength while 1 represents full jump strength.
+     * Setting power to a value above 1 will use additional jump strength
+     * that the horse does not usually have.
+     * <p>
+     * Power does not affect how high the horse is capable of jumping,
+     * only how much of its jumping capability will be used in this jump.
+     * To set the horse's overall jump strength, see
+     * {@link Horse#setJumpStrength(double)}.
+     *
+     * @return jump strength
+     */
+    public float getPower() {
+        return power;
+    }
+
+    /**
+     * Sets the power of the jump.
+     * <p>
+     * Jump power can be set to a value above 1.0 which will increase
+     * the strength of this jump above the horse's actual jump strength.
+     * <p>
+     * Setting the jump power to 0 will result in the jump animation
+     * still playing, but the horse not leaving the ground. Only
+     * canceling this event will result in no jump animation at all.
+     *
+     * @param power power of the jump
+     */
+    public void setPower(float power) {
+        this.power = power;
+    }
+
+    @Override
+    public HandlerList getHandlers() {
+        return handlers;
+    }
+
+    public static HandlerList getHandlerList() {
+        return handlers;
+    }
+}