Use proper naming convention for boolean methods.

By: Travis Watkins <amaranth@ubuntu.com>

paper-api/src/main/java/org/bukkit/entity/LivingEntity.java

@@ -317,5 +317,5 @@ public interface LivingEntity extends Entity, Damageable {
      * name.
      * @return if the custom name is displayed
      */
-    public boolean getCustomNameVisible();
+    public boolean isCustomNameVisible();
 }