Added a few null pointer checks and performed minor touchups (tried improving a few equals, clone and hashCode methods).

By: VictorD <victor.danell@gmail.com>

paper-api/src/main/java/org/bukkit/ChatColor.java

@@ -110,6 +110,9 @@ public enum ChatColor {
      * @return A copy of the input string, without any coloring
      */
     public static String stripColor(final String input) {
+        if (input == null)
+            return null;
+        
         return input.replaceAll("(?i)\u00A7[0-F]", "");
     }
 

paper-api/src/main/java/org/bukkit/Location.java

@@ -271,7 +271,19 @@ public class Location implements Cloneable {
 
     @Override
     public Location clone() {
-        return new Location(world, x, y, z, yaw, pitch);
+        try {
+            Location l = (Location)super.clone();
+            l.world = world;
+            l.x = x;
+            l.y = y;
+            l.z = z;
+            l.yaw = yaw;
+            l.pitch = pitch;
+            return l;
+        } catch (CloneNotSupportedException e) {
+            e.printStackTrace();
+        }
+        return null;
     }
 
     /**

paper-api/src/main/java/org/bukkit/fillr/Downloader.java

@@ -130,7 +130,7 @@ public class Downloader {
 	 *            The file to backup
 	 */
 	private static void backupFile(File file) {
-		if (file.exists()) {
+		if (file != null  && file.exists()) {
 			System.out.println("Backing up old file: " + file.getName());
 			if (!new File(BACKUP).exists()) {
 				new File(BACKUP).mkdir();

paper-api/src/main/java/org/bukkit/inventory/ItemStack.java

@@ -182,11 +182,19 @@ public class ItemStack {
     }
 
     @Override
-    public boolean equals(Object object) {
+    public boolean equals(Object obj) {
-        return false;
+        if (!(obj instanceof ItemStack))
-    }
+            return false;
-
+        
-    public boolean equals(ItemStack item) {
+        ItemStack item = (ItemStack)obj;
         return item.getAmount() == getAmount() && item.getTypeId() == getTypeId();
     }
+    
+    @Override
+    public int hashCode() {
+        int hash = 11;
+        hash = hash * 19 + 7 * getTypeId(); // Overriding hashCode since equals is overridden, it's just 
+        hash = hash * 7 + 23 * getAmount(); // too bad these are mutable values... Q_Q
+        return hash;
+    } 
 }

paper-api/src/main/java/org/bukkit/plugin/PluginManager.java

@@ -18,7 +18,7 @@ public interface PluginManager {
      * @param loader Class name of the PluginLoader to register
      * @throws IllegalArgumentException Thrown when the given Class is not a valid PluginLoader
      */
-    public void RegisterInterface(Class<? extends PluginLoader> loader) throws IllegalArgumentException;
+    public void registerInterface(Class<? extends PluginLoader> loader) throws IllegalArgumentException;
 
     /**
      * Checks if the given plugin is loaded and returns it when applicable

paper-api/src/main/java/org/bukkit/plugin/SimplePluginManager.java

@@ -53,7 +53,7 @@ public final class SimplePluginManager implements PluginManager {
      * @param loader Class name of the PluginLoader to register
      * @throws IllegalArgumentException Thrown when the given Class is not a valid PluginLoader
      */
-    public void RegisterInterface(Class<? extends PluginLoader> loader) throws IllegalArgumentException {
+    public void registerInterface(Class<? extends PluginLoader> loader) throws IllegalArgumentException {
         PluginLoader instance;
 
         if (PluginLoader.class.isAssignableFrom(loader)) {
@@ -62,7 +62,8 @@ public final class SimplePluginManager implements PluginManager {
                 constructor = loader.getConstructor(Server.class);
                 instance = constructor.newInstance(server);
             } catch (NoSuchMethodException ex) {
-                throw new IllegalArgumentException(String.format("Class %s does not have a public %s(Server) constructor", loader.getName()), ex);
+                String className = loader.getName();
+                throw new IllegalArgumentException(String.format("Class %s does not have a public %s(Server) constructor", className,className), ex);
             } catch (Exception ex) {
                 throw new IllegalArgumentException(String.format("Unexpected exception %s while attempting to construct a new instance of %s", ex.getClass().getName(), loader.getName()), ex);
             }

paper-api/src/main/java/org/bukkit/util/BlockIterator.java

@@ -7,10 +7,8 @@ import org.bukkit.block.BlockFace;
 import org.bukkit.entity.LivingEntity;
 
 import java.util.Iterator;
-import java.util.ArrayList;
 import java.util.NoSuchElementException;
 import java.lang.IllegalStateException;
-import java.lang.Exception;
 
 /**
  * This class performs ray tracing and iterates along blocks on a line
@@ -23,7 +21,7 @@ public class BlockIterator implements Iterator<Block> {
     private final World  world;
     private final int    maxDistance;
 
-    private final int    gridSize = 1<<24;
+    private static final int    gridSize = 1<<24;
 
     private boolean      end = false;
 

paper-api/src/main/java/org/bukkit/util/BlockVector.java

@@ -102,6 +102,10 @@ public class BlockVector extends Vector {
      */
     @Override
     public BlockVector clone() {
-        return new BlockVector(x, y, z);
+        BlockVector v = (BlockVector)super.clone();
+        v.x = x;
+        v.y = y;
+        v.z = z;
+        return v;
     }
 }

paper-api/src/main/java/org/bukkit/util/Vector.java

@@ -522,7 +522,7 @@ public class Vector implements Cloneable {
 
         return Math.abs(x - other.x) < epsilon
                 && Math.abs(y - other.y) < epsilon
-                && Math.abs(z - other.z) < epsilon;
+                && Math.abs(z - other.z) < epsilon && (this.getClass().equals(obj.getClass()));
     }
 
     /**
@@ -546,7 +546,16 @@ public class Vector implements Cloneable {
      */
     @Override
     public Vector clone() {
-        return new Vector(x, y, z);
+        try {
+            Vector v = (Vector)super.clone();
+            v.x = x;
+            v.y = y;
+            v.z = z;
+            return v;            
+        } catch (CloneNotSupportedException e) {
+            e.printStackTrace();
+        }
+        return null;
     }
 
     /**