Generic cleanup of warnings, whitespace and style.

By: Erik Broes <erikbroes@grum.nl>

paper-api/src/main/java/org/bukkit/event/painting/PaintingBreakByEntityEvent.java

@@ -6,6 +6,7 @@ import org.bukkit.entity.Painting;
 /**
  * Triggered when a painting is removed by an entity
  */
+@SuppressWarnings("serial")
 public class PaintingBreakByEntityEvent extends PaintingBreakEvent {
     private Entity remover;
 

paper-api/src/main/java/org/bukkit/event/painting/PaintingBreakEvent.java

@@ -6,6 +6,7 @@ import org.bukkit.event.Cancellable;
 /**
  * Triggered when a painting is removed
  */
+@SuppressWarnings("serial")
 public class PaintingBreakEvent extends PaintingEvent implements Cancellable {
 
     private boolean cancelled;

paper-api/src/main/java/org/bukkit/event/painting/PaintingEvent.java

@@ -6,6 +6,7 @@ import org.bukkit.event.Event;
 /**
  * Represents a painting-related event.
  */
+@SuppressWarnings("serial")
 public class PaintingEvent extends Event {
 
     protected Painting painting;

paper-api/src/main/java/org/bukkit/event/painting/PaintingPlaceEvent.java

@@ -10,6 +10,7 @@ import org.bukkit.event.Event;
 /**
  * Triggered when a painting is created in the world
  */
+@SuppressWarnings("serial")
 public class PaintingPlaceEvent extends PaintingEvent implements Cancellable {
 
     private boolean cancelled;