[CI skip] More nullability annotations

pom.xml

@@ -159,7 +159,7 @@
 
                 <configuration>
 
-                    <!-- Shade bStats and CS-CoreLib2 into the output jar -->
+                    <!-- Shade dependencies into the output jar -->
                     <relocations>
                         <relocation>
                             <pattern>org.bstats</pattern>
@@ -294,13 +294,15 @@
             <scope>provided</scope>
         </dependency>
 
-        <!-- Development / Testing dependencies -->
+        <!-- Development dependencies -->
         <dependency>
-            <groupId>javax.annotation</groupId>
+            <groupId>com.google.code.findbugs</groupId>
-            <artifactId>javax.annotation-api</artifactId>
+            <artifactId>jsr305</artifactId>
-            <version>1.3.2</version>
+            <version>3.0.2</version>
             <scope>provided</scope>
         </dependency>
+
+        <!-- Testing dependencies -->
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter</artifactId>
@@ -360,7 +362,7 @@
             </exclusions>
         </dependency>
 
-        <!-- Third party plugin integrations -->
+        <!-- Third party plugin integrations / soft dependencies -->
         <dependency>
             <groupId>com.sk89q.worldedit</groupId>
             <artifactId>worldedit-bukkit</artifactId>

src/main/java/io/github/thebusybiscuit/slimefun4/api/events/AncientAltarCraftEvent.java

@@ -1,5 +1,8 @@
 package io.github.thebusybiscuit.slimefun4.api.events;
 
+import javax.annotation.Nonnull;
+import javax.annotation.ParametersAreNonnullByDefault;
+
 import org.bukkit.Material;
 import org.bukkit.block.Block;
 import org.bukkit.entity.Player;
@@ -38,6 +41,7 @@ public class AncientAltarCraftEvent extends PlayerEvent implements Cancellable {
      * @param player
      *            The {@link Player} that started the ritual.
      */
+    @ParametersAreNonnullByDefault
     public AncientAltarCraftEvent(ItemStack output, Block block, Player player) {
         super(player);
 
@@ -50,6 +54,7 @@ public class AncientAltarCraftEvent extends PlayerEvent implements Cancellable {
      *
      * @return the main altar's block {@link Block}
      */
+    @Nonnull
     public Block getAltarBlock() {
         return block;
     }
@@ -59,6 +64,7 @@ public class AncientAltarCraftEvent extends PlayerEvent implements Cancellable {
      *
      * @return the {@link ItemStack} that would be dropped by the {@link AncientAltar}
      */
+    @Nonnull
     public ItemStack getItem() {
         return output;
     }
@@ -87,10 +93,12 @@ public class AncientAltarCraftEvent extends PlayerEvent implements Cancellable {
         cancelled = cancel;
     }
 
+    @Nonnull
     public static HandlerList getHandlerList() {
         return handlers;
     }
 
+    @Nonnull
     @Override
     public HandlerList getHandlers() {
         return getHandlerList();

src/main/java/io/github/thebusybiscuit/slimefun4/api/events/AndroidMineEvent.java

@@ -1,5 +1,8 @@
 package io.github.thebusybiscuit.slimefun4.api.events;
 
+import javax.annotation.Nonnull;
+import javax.annotation.ParametersAreNonnullByDefault;
+
 import org.bukkit.block.Block;
 import org.bukkit.event.Cancellable;
 import org.bukkit.event.Event;
@@ -29,6 +32,7 @@ public class AndroidMineEvent extends Event implements Cancellable {
      * @param android
      *            The {@link AndroidInstance} that triggered this {@link Event}
      */
+    @ParametersAreNonnullByDefault
     public AndroidMineEvent(Block block, AndroidInstance android) {
         this.block = block;
         this.android = android;
@@ -39,6 +43,7 @@ public class AndroidMineEvent extends Event implements Cancellable {
      *
      * @return the mined {@link Block}
      */
+    @Nonnull
     public Block getBlock() {
         return block;
     }
@@ -49,6 +54,7 @@ public class AndroidMineEvent extends Event implements Cancellable {
      *
      * @return the involved {@link AndroidInstance}
      */
+    @Nonnull
     public AndroidInstance getAndroid() {
         return android;
     }
@@ -63,10 +69,12 @@ public class AndroidMineEvent extends Event implements Cancellable {
         cancelled = cancel;
     }
 
+    @Nonnull
     public static HandlerList getHandlerList() {
         return handlers;
     }
 
+    @Nonnull
     @Override
     public HandlerList getHandlers() {
         return getHandlerList();

src/main/java/io/github/thebusybiscuit/slimefun4/api/events/AutoDisenchantEvent.java

@@ -1,5 +1,7 @@
 package io.github.thebusybiscuit.slimefun4.api.events;
 
+import javax.annotation.Nonnull;
+
 import org.bukkit.event.Cancellable;
 import org.bukkit.event.Event;
 import org.bukkit.event.HandlerList;
@@ -21,7 +23,7 @@ public class AutoDisenchantEvent extends Event implements Cancellable {
     private final ItemStack item;
     private boolean cancelled;
 
-    public AutoDisenchantEvent(ItemStack item) {
+    public AutoDisenchantEvent(@Nonnull ItemStack item) {
         super(true);
 
         this.item = item;
@@ -32,13 +34,14 @@ public class AutoDisenchantEvent extends Event implements Cancellable {
      * 
      * @return The {@link ItemStack} that is being disenchanted
      */
+    @Nonnull
     public ItemStack getItem() {
-        return this.item;
+        return item;
     }
 
     @Override
     public boolean isCancelled() {
-        return this.cancelled;
+        return cancelled;
     }
 
     @Override
@@ -46,10 +49,12 @@ public class AutoDisenchantEvent extends Event implements Cancellable {
         this.cancelled = cancel;
     }
 
+    @Nonnull
     public static HandlerList getHandlerList() {
         return handlers;
     }
 
+    @Nonnull
     @Override
     public HandlerList getHandlers() {
         return getHandlerList();

src/main/java/io/github/thebusybiscuit/slimefun4/api/events/BlockPlacerPlaceEvent.java

@@ -1,5 +1,8 @@
 package io.github.thebusybiscuit.slimefun4.api.events;
 
+import javax.annotation.Nonnull;
+import javax.annotation.ParametersAreNonnullByDefault;
+
 import org.apache.commons.lang.Validate;
 import org.bukkit.block.Block;
 import org.bukkit.event.Cancellable;
@@ -37,6 +40,7 @@ public class BlockPlacerPlaceEvent extends BlockEvent implements Cancellable {
      * @param block
      *            The placed {@link Block}
      */
+    @ParametersAreNonnullByDefault
     public BlockPlacerPlaceEvent(Block blockPlacer, ItemStack placedItem, Block block) {
         super(block);
 
@@ -49,6 +53,7 @@ public class BlockPlacerPlaceEvent extends BlockEvent implements Cancellable {
      *
      * @return The {@link BlockPlacer}
      */
+    @Nonnull
     public Block getBlockPlacer() {
         return blockPlacer;
     }
@@ -58,6 +63,7 @@ public class BlockPlacerPlaceEvent extends BlockEvent implements Cancellable {
      * 
      * @return The placed {@link ItemStack}
      */
+    @Nonnull
     public ItemStack getItemStack() {
         return placedItem;
     }
@@ -68,7 +74,7 @@ public class BlockPlacerPlaceEvent extends BlockEvent implements Cancellable {
      * @param item
      *            The {@link ItemStack} to be placed
      */
-    public void setItemStack(ItemStack item) {
+    public void setItemStack(@Nonnull ItemStack item) {
         Validate.notNull(item, "The ItemStack must not be null!");
 
         if (!locked) {
@@ -101,10 +107,12 @@ public class BlockPlacerPlaceEvent extends BlockEvent implements Cancellable {
         locked = true;
     }
 
+    @Nonnull
     public static HandlerList getHandlerList() {
         return handlers;
     }
 
+    @Nonnull
     @Override
     public HandlerList getHandlers() {
         return getHandlerList();

src/main/java/io/github/thebusybiscuit/slimefun4/api/events/ClimbingPickLaunchEvent.java

@@ -1,5 +1,8 @@
 package io.github.thebusybiscuit.slimefun4.api.events;
 
+import javax.annotation.Nonnull;
+import javax.annotation.ParametersAreNonnullByDefault;
+
 import org.apache.commons.lang.Validate;
 import org.bukkit.block.Block;
 import org.bukkit.entity.Player;
@@ -32,6 +35,7 @@ public class ClimbingPickLaunchEvent extends PlayerEvent implements Cancellable
 
     private boolean cancelled;
 
+    @ParametersAreNonnullByDefault
     public ClimbingPickLaunchEvent(Player player, Vector velocity, ClimbingPick pick, ItemStack itemStack, Block block) {
         super(player);
 
@@ -47,6 +51,7 @@ public class ClimbingPickLaunchEvent extends PlayerEvent implements Cancellable
      *
      * @return The {@link Vector} of the applied velocity
      */
+    @Nonnull
     public Vector getVelocity() {
         return velocity;
     }
@@ -57,7 +62,7 @@ public class ClimbingPickLaunchEvent extends PlayerEvent implements Cancellable
      * @param velocity
      *            The {@link Vector} velocity to apply
      */
-    public void setVelocity(Vector velocity) {
+    public void setVelocity(@Nonnull Vector velocity) {
         Validate.notNull(velocity);
         this.velocity = velocity;
     }
@@ -67,8 +72,9 @@ public class ClimbingPickLaunchEvent extends PlayerEvent implements Cancellable
      *
      * @return The {@link ClimbingPick} that was used
      */
+    @Nonnull
     public ClimbingPick getPick() {
-        return this.pick;
+        return pick;
     }
 
     /**
@@ -76,8 +82,9 @@ public class ClimbingPickLaunchEvent extends PlayerEvent implements Cancellable
      *
      * @return The {@link ItemStack} that was used
      */
+    @Nonnull
     public ItemStack getItemStack() {
-        return this.itemStack;
+        return itemStack;
     }
 
     /**
@@ -85,13 +92,14 @@ public class ClimbingPickLaunchEvent extends PlayerEvent implements Cancellable
      *
      * @return The {@link Block} that was climbed
      */
+    @Nonnull
     public Block getBlock() {
-        return this.block;
+        return block;
     }
 
     @Override
     public boolean isCancelled() {
-        return this.cancelled;
+        return cancelled;
     }
 
     @Override
@@ -99,10 +107,12 @@ public class ClimbingPickLaunchEvent extends PlayerEvent implements Cancellable
         this.cancelled = cancel;
     }
 
+    @Nonnull
     public static HandlerList getHandlerList() {
         return handlers;
     }
 
+    @Nonnull
     @Override
     public HandlerList getHandlers() {
         return getHandlerList();

src/main/java/io/github/thebusybiscuit/slimefun4/api/events/GEOResourceGenerationEvent.java

@@ -1,5 +1,8 @@
 package io.github.thebusybiscuit.slimefun4.api.events;
 
+import javax.annotation.Nonnull;
+import javax.annotation.ParametersAreNonnullByDefault;
+
 import org.bukkit.Chunk;
 import org.bukkit.Location;
 import org.bukkit.World;
@@ -38,6 +41,7 @@ public class GEOResourceGenerationEvent extends Event {
 
     private int value;
 
+    @ParametersAreNonnullByDefault
     public GEOResourceGenerationEvent(World world, Biome biome, int x, int z, GEOResource resource, int value) {
         this.world = world;
         this.biome = biome;
@@ -76,6 +80,7 @@ public class GEOResourceGenerationEvent extends Event {
      * 
      * @return The affected {@link World}
      */
+    @Nonnull
     public World getWorld() {
         return world;
     }
@@ -85,6 +90,7 @@ public class GEOResourceGenerationEvent extends Event {
      * 
      * @return The generated {@link GEOResource}
      */
+    @Nonnull
     public GEOResource getResource() {
         return resource;
     }
@@ -115,6 +121,7 @@ public class GEOResourceGenerationEvent extends Event {
      * 
      * @return The {@link Environment} of this generation
      */
+    @Nonnull
     public Environment getEnvironment() {
         return world.getEnvironment();
     }
@@ -125,6 +132,7 @@ public class GEOResourceGenerationEvent extends Event {
      * 
      * @return The {@link Biome} of this generation
      */
+    @Nonnull
     public Biome getBiome() {
         return biome;
     }

src/main/java/io/github/thebusybiscuit/slimefun4/api/events/MultiBlockInteractEvent.java

@@ -1,5 +1,8 @@
 package io.github.thebusybiscuit.slimefun4.api.events;
 
+import javax.annotation.Nonnull;
+import javax.annotation.ParametersAreNonnullByDefault;
+
 import org.bukkit.block.Block;
 import org.bukkit.block.BlockFace;
 import org.bukkit.entity.Player;
@@ -25,6 +28,7 @@ public class MultiBlockInteractEvent extends PlayerEvent implements Cancellable
     private final BlockFace clickedFace;
     private boolean cancelled;
 
+    @ParametersAreNonnullByDefault
     public MultiBlockInteractEvent(Player p, MultiBlock mb, Block clicked, BlockFace face) {
         super(p);
         this.multiBlock = mb;
@@ -37,6 +41,7 @@ public class MultiBlockInteractEvent extends PlayerEvent implements Cancellable
      * 
      * @return The {@link MultiBlock} of this {@link MultiBlockInteractEvent}
      */
+    @Nonnull
     public MultiBlock getMultiBlock() {
         return multiBlock;
     }
@@ -46,6 +51,7 @@ public class MultiBlockInteractEvent extends PlayerEvent implements Cancellable
      * 
      * @return The {@link Block} that was clicked
      */
+    @Nonnull
     public Block getClickedBlock() {
         return clickedBlock;
     }
@@ -55,6 +61,7 @@ public class MultiBlockInteractEvent extends PlayerEvent implements Cancellable
      * 
      * @return The {@link BlockFace} that was clicked
      */
+    @Nonnull
     public BlockFace getClickedFace() {
         return clickedFace;
     }
@@ -69,10 +76,12 @@ public class MultiBlockInteractEvent extends PlayerEvent implements Cancellable
         this.cancelled = cancel;
     }
 
+    @Nonnull
     public static HandlerList getHandlerList() {
         return handlers;
     }
 
+    @Nonnull
     @Override
     public HandlerList getHandlers() {
         return getHandlerList();

src/main/java/io/github/thebusybiscuit/slimefun4/api/events/PlayerLanguageChangeEvent.java

@@ -1,5 +1,7 @@
 package io.github.thebusybiscuit.slimefun4.api.events;
 
+import javax.annotation.Nonnull;
+
 import org.bukkit.entity.Player;
 import org.bukkit.event.Event;
 import org.bukkit.event.HandlerList;
@@ -24,7 +26,7 @@ public class PlayerLanguageChangeEvent extends Event {
     private final Language from;
     private final Language to;
 
-    public PlayerLanguageChangeEvent(Player p, Language from, Language to) {
+    public PlayerLanguageChangeEvent(@Nonnull Player p, @Nonnull Language from, @Nonnull Language to) {
         player = p;
         this.from = from;
         this.to = to;
@@ -36,6 +38,7 @@ public class PlayerLanguageChangeEvent extends Event {
      * 
      * @return The {@link Player} who switched his {@link Language}
      */
+    @Nonnull
     public Player getPlayer() {
         return player;
     }
@@ -45,6 +48,7 @@ public class PlayerLanguageChangeEvent extends Event {
      * 
      * @return The previous {@link Language} of our {@link Player}
      */
+    @Nonnull
     public Language getPreviousLanguage() {
         return from;
     }
@@ -54,6 +58,7 @@ public class PlayerLanguageChangeEvent extends Event {
      * 
      * @return The new {@link Language}
      */
+    @Nonnull
     public Language getNewLanguage() {
         return to;
     }

src/main/java/io/github/thebusybiscuit/slimefun4/api/events/PlayerRightClickEvent.java

@@ -2,6 +2,9 @@ package io.github.thebusybiscuit.slimefun4.api.events;
 
 import java.util.Optional;
 
+import javax.annotation.Nonnull;
+
+import org.apache.commons.lang.Validate;
 import org.bukkit.Material;
 import org.bukkit.block.Block;
 import org.bukkit.block.BlockFace;
@@ -35,7 +38,7 @@ public class PlayerRightClickEvent extends Event {
     private Result itemResult = Result.DEFAULT;
     private Result blockResult = Result.DEFAULT;
 
-    public PlayerRightClickEvent(PlayerInteractEvent e) {
+    public PlayerRightClickEvent(@Nonnull PlayerInteractEvent e) {
         event = e;
         player = e.getPlayer();
         clickedBlock = Optional.ofNullable(e.getClickedBlock());
@@ -50,10 +53,12 @@ public class PlayerRightClickEvent extends Event {
         }
     }
 
+    @Nonnull
     public PlayerInteractEvent getInteractEvent() {
         return event;
     }
 
+    @Nonnull
     public Player getPlayer() {
         return player;
     }
@@ -65,6 +70,7 @@ public class PlayerRightClickEvent extends Event {
      * 
      * @return The {@link ItemStack} that the {@link Player} right clicked with
      */
+    @Nonnull
     public ItemStack getItem() {
         return itemStack.orElse(new ItemStack(Material.AIR));
     }
@@ -75,20 +81,23 @@ public class PlayerRightClickEvent extends Event {
      * 
      * @return The hand used in this {@link Event}
      */
+    @Nonnull
     public EquipmentSlot getHand() {
         return hand;
     }
 
+    @Nonnull
     public Optional<Block> getClickedBlock() {
         return clickedBlock;
     }
 
+    @Nonnull
     public BlockFace getClickedFace() {
         return face;
     }
 
+    @Nonnull
     public Optional<SlimefunItem> getSlimefunItem() {
-
         if (!slimefunItem.isComputed()) {
             if (itemStack.isPresent()) {
                 slimefunItem.compute(SlimefunItem.getByItem(itemStack.get()));
@@ -101,8 +110,8 @@ public class PlayerRightClickEvent extends Event {
         return slimefunItem.getAsOptional();
     }
 
+    @Nonnull
     public Optional<SlimefunItem> getSlimefunBlock() {
-
         if (!slimefunBlock.isComputed()) {
             if (clickedBlock.isPresent()) {
                 slimefunBlock.compute(BlockStorage.check(clickedBlock.get()));
@@ -120,26 +129,32 @@ public class PlayerRightClickEvent extends Event {
         blockResult = Result.DENY;
     }
 
+    @Nonnull
     public Result useItem() {
         return itemResult;
     }
 
+    @Nonnull
     public Result useBlock() {
         return blockResult;
     }
 
-    public void setUseItem(Result result) {
+    public void setUseItem(@Nonnull Result result) {
+        Validate.notNull(result, "Result cannot be null");
         itemResult = result;
     }
 
-    public void setUseBlock(Result result) {
+    public void setUseBlock(@Nonnull Result result) {
+        Validate.notNull(result, "Result cannot be null");
         blockResult = result;
     }
 
+    @Nonnull
     public static HandlerList getHandlerList() {
         return handlers;
     }
 
+    @Nonnull
     @Override
     public HandlerList getHandlers() {
         return getHandlerList();

src/main/java/io/github/thebusybiscuit/slimefun4/api/events/ReactorExplodeEvent.java

@@ -1,5 +1,7 @@
 package io.github.thebusybiscuit.slimefun4.api.events;
 
+import javax.annotation.Nonnull;
+
 import org.apache.commons.lang.Validate;
 import org.bukkit.Location;
 import org.bukkit.event.Event;
@@ -21,7 +23,7 @@ public class ReactorExplodeEvent extends Event {
     private final Location location;
     private final Reactor reactor;
 
-    public ReactorExplodeEvent(Location l, Reactor reactor) {
+    public ReactorExplodeEvent(@Nonnull Location l, @Nonnull Reactor reactor) {
         Validate.notNull(l, "A Location must be provided");
         Validate.notNull(reactor, "A Reactor cannot be null");
 
@@ -34,6 +36,7 @@ public class ReactorExplodeEvent extends Event {
      * 
      * @return The {@link Location} of this explosion
      */
+    @Nonnull
     public Location getLocation() {
         return location;
     }
@@ -43,14 +46,17 @@ public class ReactorExplodeEvent extends Event {
      * 
      * @return The {@link SlimefunItem} instance
      */
+    @Nonnull
     public Reactor getReactor() {
         return reactor;
     }
 
+    @Nonnull
     public static HandlerList getHandlerList() {
         return handlers;
     }
 
+    @Nonnull
     @Override
     public HandlerList getHandlers() {
         return getHandlerList();

src/main/java/io/github/thebusybiscuit/slimefun4/api/events/ResearchUnlockEvent.java

@@ -1,5 +1,8 @@
 package io.github.thebusybiscuit.slimefun4.api.events;
 
+import javax.annotation.Nonnull;
+
+import org.apache.commons.lang.Validate;
 import org.bukkit.entity.Player;
 import org.bukkit.event.Cancellable;
 import org.bukkit.event.Event;
@@ -23,15 +26,19 @@ public class ResearchUnlockEvent extends Event implements Cancellable {
     private final Research research;
     private boolean cancelled;
 
-    public ResearchUnlockEvent(Player p, Research research) {
+    public ResearchUnlockEvent(@Nonnull Player p, @Nonnull Research research) {
+        Validate.notNull(p, "The Player cannot be null");
+        Validate.notNull(research, "Research cannot be null");
         this.player = p;
         this.research = research;
     }
 
+    @Nonnull
     public Player getPlayer() {
         return player;
     }
 
+    @Nonnull
     public Research getResearch() {
         return research;
     }
@@ -46,10 +53,12 @@ public class ResearchUnlockEvent extends Event implements Cancellable {
         this.cancelled = cancel;
     }
 
+    @Nonnull
     public static HandlerList getHandlerList() {
         return handlers;
     }
 
+    @Nonnull
     @Override
     public HandlerList getHandlers() {
         return getHandlerList();

src/main/java/io/github/thebusybiscuit/slimefun4/api/events/WaypointCreateEvent.java

@@ -1,5 +1,7 @@
 package io.github.thebusybiscuit.slimefun4.api.events;
 
+import javax.annotation.Nonnull;
+
 import org.apache.commons.lang.Validate;
 import org.bukkit.Location;
 import org.bukkit.entity.Player;
@@ -32,7 +34,7 @@ public class WaypointCreateEvent extends PlayerEvent implements Cancellable {
     private final boolean deathpoint;
     private boolean cancelled;
 
-    public WaypointCreateEvent(Player player, String name, Location location) {
+    public WaypointCreateEvent(@Nonnull Player player, @Nonnull String name, @Nonnull Location location) {
         super(player);
 
         Validate.notNull(location, "Location must not be null!");
@@ -48,6 +50,7 @@ public class WaypointCreateEvent extends PlayerEvent implements Cancellable {
      * 
      * @return The {@link Location} of this waypoint
      */
+    @Nonnull
     public Location getLocation() {
         return location;
     }
@@ -59,7 +62,7 @@ public class WaypointCreateEvent extends PlayerEvent implements Cancellable {
      * @param loc
      *            The {@link Location} to set
      */
-    public void setLocation(Location loc) {
+    public void setLocation(@Nonnull Location loc) {
         Validate.notNull(loc, "Cannot set the Location to null!");
         this.location = loc;
     }
@@ -69,6 +72,7 @@ public class WaypointCreateEvent extends PlayerEvent implements Cancellable {
      * 
      * @return The name of this waypoint
      */
+    @Nonnull
     public String getName() {
         return name;
     }
@@ -79,7 +83,7 @@ public class WaypointCreateEvent extends PlayerEvent implements Cancellable {
      * @param name
      *            The name for this waypoint
      */
-    public void setName(String name) {
+    public void setName(@Nonnull String name) {
         Validate.notEmpty(name, "The name of a waypoint must not be empty!");
         this.name = name;
     }
@@ -104,10 +108,12 @@ public class WaypointCreateEvent extends PlayerEvent implements Cancellable {
         this.cancelled = cancel;
     }
 
+    @Nonnull
     public static HandlerList getHandlerList() {
         return handlers;
     }
 
+    @Nonnull
     @Override
     public HandlerList getHandlers() {
         return getHandlerList();

src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/RadioactiveItem.java

@@ -1,6 +1,7 @@
 package io.github.thebusybiscuit.slimefun4.implementation.items;
 
 import javax.annotation.Nonnull;
+import javax.annotation.ParametersAreNonnullByDefault;
 
 import org.bukkit.inventory.ItemStack;
 
@@ -45,6 +46,7 @@ public class RadioactiveItem extends SlimefunItem implements Radioactive, NotPla
      * @param recipe
      *            The recipe of how to craft this {@link SlimefunItem}
      */
+    @ParametersAreNonnullByDefault
     public RadioactiveItem(Category category, Radioactivity radioactivity, SlimefunItemStack item, RecipeType recipeType, ItemStack[] recipe) {
         this(category, radioactivity, item, recipeType, recipe, null);
     }
@@ -65,6 +67,7 @@ public class RadioactiveItem extends SlimefunItem implements Radioactive, NotPla
      * @param recipeOutput
      *            The recipe output
      */
+    @ParametersAreNonnullByDefault
     public RadioactiveItem(Category category, Radioactivity radioactivity, SlimefunItemStack item, RecipeType recipeType, ItemStack[] recipe, ItemStack recipeOutput) {
         super(category, item, recipeType, recipe, recipeOutput);
 

src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/SimpleSlimefunItem.java

@@ -1,6 +1,7 @@
 package io.github.thebusybiscuit.slimefun4.implementation.items;
 
 import javax.annotation.Nonnull;
+import javax.annotation.ParametersAreNonnullByDefault;
 
 import org.bukkit.inventory.ItemStack;
 
@@ -29,10 +30,12 @@ import me.mrCookieSlime.Slimefun.api.SlimefunItemStack;
  */
 public abstract class SimpleSlimefunItem<T extends ItemHandler> extends SlimefunItem {
 
+    @ParametersAreNonnullByDefault
     public SimpleSlimefunItem(Category category, SlimefunItemStack item, RecipeType recipeType, ItemStack[] recipe) {
         super(category, item, recipeType, recipe);
     }
 
+    @ParametersAreNonnullByDefault
     public SimpleSlimefunItem(Category category, SlimefunItemStack item, RecipeType recipeType, ItemStack[] recipe, ItemStack recipeOutput) {
         super(category, item, recipeType, recipe, recipeOutput);
     }

src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/VanillaItem.java

@@ -1,5 +1,7 @@
 package io.github.thebusybiscuit.slimefun4.implementation.items;
 
+import javax.annotation.ParametersAreNonnullByDefault;
+
 import org.bukkit.inventory.ItemStack;
 
 import io.github.thebusybiscuit.slimefun4.api.items.ItemState;
@@ -38,6 +40,7 @@ public class VanillaItem extends SlimefunItem {
      * @param recipe
      *            the recipe to obtain this {@link VanillaItem}
      */
+    @ParametersAreNonnullByDefault
     public VanillaItem(Category category, ItemStack item, String id, RecipeType recipeType, ItemStack[] recipe) {
         super(category, item, id, recipeType, recipe);
 

src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/electric/AbstractEnergyProvider.java

@@ -6,6 +6,7 @@ import java.util.List;
 import java.util.Set;
 
 import javax.annotation.Nonnull;
+import javax.annotation.ParametersAreNonnullByDefault;
 
 import org.bukkit.inventory.Inventory;
 import org.bukkit.inventory.ItemStack;
@@ -40,6 +41,7 @@ public abstract class AbstractEnergyProvider extends SlimefunItem implements Inv
 
     protected final Set<MachineFuel> fuelTypes = new HashSet<>();
 
+    @ParametersAreNonnullByDefault
     protected AbstractEnergyProvider(Category category, SlimefunItemStack item, RecipeType recipeType, ItemStack[] recipe) {
         super(category, item, recipeType, recipe);
     }
@@ -81,6 +83,7 @@ public abstract class AbstractEnergyProvider extends SlimefunItem implements Inv
     protected abstract void registerDefaultFuelTypes();
 
     @Override
+    @Nonnull
     public EnergyNetComponentType getEnergyComponentType() {
         return EnergyNetComponentType.GENERATOR;
     }

src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/electric/Capacitor.java

@@ -1,5 +1,8 @@
 package io.github.thebusybiscuit.slimefun4.implementation.items.electric;
 
+import javax.annotation.Nonnull;
+import javax.annotation.ParametersAreNonnullByDefault;
+
 import org.bukkit.inventory.ItemStack;
 
 import io.github.thebusybiscuit.slimefun4.core.attributes.EnergyNetComponent;
@@ -26,6 +29,7 @@ public class Capacitor extends SlimefunItem implements EnergyNetComponent {
 
     private final int capacity;
 
+    @ParametersAreNonnullByDefault
     public Capacitor(Category category, int capacity, SlimefunItemStack item, RecipeType recipeType, ItemStack[] recipe) {
         super(category, item, recipeType, recipe);
 
@@ -33,6 +37,7 @@ public class Capacitor extends SlimefunItem implements EnergyNetComponent {
     }
 
     @Override
+    @Nonnull
     public EnergyNetComponentType getEnergyComponentType() {
         return EnergyNetComponentType.CAPACITOR;
     }

src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/electric/EnergyRegulator.java

@@ -1,6 +1,7 @@
 package io.github.thebusybiscuit.slimefun4.implementation.items.electric;
 
 import javax.annotation.Nonnull;
+import javax.annotation.ParametersAreNonnullByDefault;
 
 import org.bukkit.block.Block;
 import org.bukkit.event.block.BlockPlaceEvent;
@@ -29,6 +30,7 @@ import me.mrCookieSlime.Slimefun.api.SlimefunItemStack;
  */
 public class EnergyRegulator extends SlimefunItem {
 
+    @ParametersAreNonnullByDefault
     public EnergyRegulator(Category category, SlimefunItemStack item, RecipeType recipeType, ItemStack[] recipe) {
         super(category, item, recipeType, recipe);
 

src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/electric/gadgets/Multimeter.java

@@ -2,6 +2,8 @@ package io.github.thebusybiscuit.slimefun4.implementation.items.electric.gadgets
 
 import java.util.Optional;
 
+import javax.annotation.ParametersAreNonnullByDefault;
+
 import org.bukkit.Location;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
@@ -28,6 +30,7 @@ import me.mrCookieSlime.Slimefun.api.SlimefunItemStack;
  */
 public class Multimeter extends SimpleSlimefunItem<ItemUseHandler> {
 
+    @ParametersAreNonnullByDefault
     public Multimeter(Category category, SlimefunItemStack item, RecipeType recipeType, ItemStack[] recipe) {
         super(category, item, recipeType, recipe);
     }

src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/electric/gadgets/SolarHelmet.java

@@ -1,5 +1,9 @@
 package io.github.thebusybiscuit.slimefun4.implementation.items.electric.gadgets;
 
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import javax.annotation.ParametersAreNonnullByDefault;
+
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 
@@ -27,6 +31,7 @@ public class SolarHelmet extends SlimefunItem {
 
     private final ItemSetting<Double> charge;
 
+    @ParametersAreNonnullByDefault
     public SolarHelmet(Category category, SlimefunItemStack item, RecipeType recipeType, ItemStack[] recipe, double defaultChargingLevel) {
         super(category, item, recipeType, recipe);
 
@@ -45,7 +50,7 @@ public class SolarHelmet extends SlimefunItem {
      * @param p
      *            The {@link Player} wearing this {@link SolarHelmet}
      */
-    public void rechargeItems(Player p) {
+    public void rechargeItems(@Nonnull Player p) {
         recharge(p.getInventory().getHelmet());
         recharge(p.getInventory().getChestplate());
         recharge(p.getInventory().getLeggings());
@@ -54,7 +59,7 @@ public class SolarHelmet extends SlimefunItem {
         recharge(p.getInventory().getItemInOffHand());
     }
 
-    private void recharge(ItemStack item) {
+    private void recharge(@Nullable ItemStack item) {
         SlimefunItem sfItem = SlimefunItem.getByItem(item);
 
         if (sfItem instanceof Rechargeable) {

src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/electric/reactors/NetherStarReactor.java

@@ -1,5 +1,8 @@
 package io.github.thebusybiscuit.slimefun4.implementation.items.electric.reactors;
 
+import javax.annotation.Nonnull;
+import javax.annotation.ParametersAreNonnullByDefault;
+
 import org.bukkit.Location;
 import org.bukkit.Material;
 import org.bukkit.entity.ArmorStand;
@@ -28,6 +31,7 @@ import me.mrCookieSlime.Slimefun.api.SlimefunItemStack;
  */
 public abstract class NetherStarReactor extends Reactor {
 
+    @ParametersAreNonnullByDefault
     public NetherStarReactor(Category category, SlimefunItemStack item, RecipeType recipeType, ItemStack[] recipe) {
         super(category, item, recipeType, recipe);
     }
@@ -38,7 +42,7 @@ public abstract class NetherStarReactor extends Reactor {
     }
 
     @Override
-    public void extraTick(Location l) {
+    public void extraTick(@Nonnull Location l) {
         Slimefun.runSync(() -> {
             ArmorStand hologram = ReactorHologram.getArmorStand(l, true);
             for (Entity entity : hologram.getNearbyEntities(5, 5, 5)) {

src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/electric/reactors/NuclearReactor.java

@@ -1,5 +1,8 @@
 package io.github.thebusybiscuit.slimefun4.implementation.items.electric.reactors;
 
+import javax.annotation.Nonnull;
+import javax.annotation.ParametersAreNonnullByDefault;
+
 import org.bukkit.Location;
 import org.bukkit.inventory.ItemStack;
 
@@ -22,6 +25,7 @@ import me.mrCookieSlime.Slimefun.api.SlimefunItemStack;
  */
 public abstract class NuclearReactor extends Reactor {
 
+    @ParametersAreNonnullByDefault
     public NuclearReactor(Category category, SlimefunItemStack item, RecipeType recipeType, ItemStack[] recipe) {
         super(category, item, recipeType, recipe);
     }
@@ -49,7 +53,7 @@ public abstract class NuclearReactor extends Reactor {
     }
 
     @Override
-    public void extraTick(Location l) {
+    public void extraTick(@Nonnull Location l) {
         // This machine does not need to perform anything while ticking
         // The Nether Star Reactor uses this method to generate the Wither Effect
     }

src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/electric/reactors/Reactor.java

@@ -76,6 +76,7 @@ public abstract class Reactor extends AbstractEnergyProvider {
 
     private final Set<Location> explosionsQueue = new HashSet<>();
 
+    @ParametersAreNonnullByDefault
     public Reactor(Category category, SlimefunItemStack item, RecipeType recipeType, ItemStack[] recipe) {
         super(category, item, recipeType, recipe);