Make IStorage return NonNull ItemStack/FluidStack

src/main/java/com/raoulvdberge/refinedstorage/api/network/grid/handler/IItemGridHandler.java

@@ -3,6 +3,7 @@ package com.raoulvdberge.refinedstorage.api.network.grid.handler;
 import net.minecraft.entity.player.ServerPlayerEntity;
 import net.minecraft.item.ItemStack;
 
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.UUID;
 
@@ -30,7 +31,7 @@ public interface IItemGridHandler {
      * @param stack  the item we're trying to insert
      * @return the remainder, or null if there is no remainder
      */
-    @Nullable
+    @Nonnull
     ItemStack onInsert(ServerPlayerEntity player, ItemStack stack);
 
     /**
@@ -48,6 +49,8 @@ public interface IItemGridHandler {
      * @param stack  the stack
      * @return the remainder stack
      */
+    // TODO Maybe remove?
+    @Nonnull
     ItemStack onShiftClick(ServerPlayerEntity player, ItemStack stack);
 
     /**

src/main/java/com/raoulvdberge/refinedstorage/api/storage/IStorage.java

@@ -28,12 +28,12 @@ public interface IStorage<T> {
     /**
      * Inserts a stack to this storage.
      *
-     * @param stack  the stack prototype to insert, do NOT modify
+     * @param stack  the stack prototype to insert, can be empty, do NOT modify
      * @param size   the amount of that prototype that has to be inserted
      * @param action the action
-     * @return null if the insert was successful, or a stack with the remainder
+     * @return an empty stack if the insert was successful, or a stack with the remainder
      */
-    @Nullable
+    @Nonnull
     T insert(@Nonnull T stack, int size, Action action);
 
     /**
@@ -41,13 +41,13 @@ public interface IStorage<T> {
      * <p>
      * If the stack we found in the system is smaller than the requested size, return that stack anyway.
      *
-     * @param stack  a prototype of the stack to extract, do NOT modify
+     * @param stack  a prototype of the stack to extract, can be empty, do NOT modify
      * @param size   the amount of that prototype that has to be extracted
      * @param flags  the flags to compare on, see {@link IComparer}
      * @param action the action
-     * @return null if we didn't extract anything, or a stack with the result
+     * @return an empty stack if nothing was extracted, or an extracted stack
      */
-    @Nullable
+    @Nonnull
     T extract(@Nonnull T stack, int size, int flags, Action action);
 
     /**

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/autocrafting/task/CraftingTask.java

@@ -611,7 +611,7 @@ public class CraftingTask implements ICraftingTask {
                 for (StackListEntry<ItemStack> need : c.getToExtract().getStacks()) {
                     ItemStack result = this.internalStorage.extract(need.getStack(), need.getStack().getCount(), DEFAULT_EXTRACT_FLAGS, Action.SIMULATE);
 
-                    if (result == null || result.getCount() != need.getStack().getCount()) {
+                    if (result.getCount() != need.getStack().getCount()) {
                         hasAll = false;
 
                         break;
@@ -622,7 +622,7 @@ public class CraftingTask implements ICraftingTask {
                     for (StackListEntry<ItemStack> need : c.getToExtract().getStacks()) {
                         ItemStack result = this.internalStorage.extract(need.getStack(), need.getStack().getCount(), DEFAULT_EXTRACT_FLAGS, Action.PERFORM);
 
-                        if (result == null || result.getCount() != need.getStack().getCount()) {
+                        if (result.getCount() != need.getStack().getCount()) {
                             throw new IllegalStateException("Extractor check lied");
                         }
                     }
@@ -701,7 +701,7 @@ public class CraftingTask implements ICraftingTask {
                         } else {
                             ItemStack result = this.internalStorage.extract(need.getStack(), need.getStack().getCount(), DEFAULT_EXTRACT_FLAGS, Action.SIMULATE);
 
-                            if (result == null || result.getCount() != need.getStack().getCount()) {
+                            if (result.getCount() != need.getStack().getCount()) {
                                 hasAll = false;
 
                                 break;
@@ -721,7 +721,7 @@ public class CraftingTask implements ICraftingTask {
                         } else {
                             FluidStack result = this.internalFluidStorage.extract(need.getStack(), need.getStack().getAmount(), IComparer.COMPARE_NBT, Action.SIMULATE);
 
-                            if (result == null || result.getAmount() != need.getStack().getAmount()) {
+                            if (result.getAmount() != need.getStack().getAmount()) {
                                 hasAll = false;
 
                                 break;
@@ -740,7 +740,7 @@ public class CraftingTask implements ICraftingTask {
 
                         for (StackListEntry<ItemStack> need : p.getItemsToPut().getStacks()) {
                             ItemStack result = this.internalStorage.extract(need.getStack(), need.getStack().getCount(), DEFAULT_EXTRACT_FLAGS, Action.PERFORM);
-                            if (result == null || result.getCount() != need.getStack().getCount()) {
+                            if (result.getCount() != need.getStack().getCount()) {
                                 throw new IllegalStateException("The internal crafting inventory reported that " + need.getStack() + " was available but we got " + result);
                             }
 
@@ -753,7 +753,7 @@ public class CraftingTask implements ICraftingTask {
 
                         for (StackListEntry<FluidStack> need : p.getFluidsToPut().getStacks()) {
                             FluidStack result = this.internalFluidStorage.extract(need.getStack(), need.getStack().getAmount(), IComparer.COMPARE_NBT, Action.PERFORM);
-                            if (result == null || result.getAmount() != need.getStack().getAmount()) {
+                            if (result.getAmount() != need.getStack().getAmount()) {
                                 throw new IllegalStateException("The internal crafting inventory reported that " + need + " was available but we got " + result);
                             }
 

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/grid/handler/FluidGridHandler.java

@@ -59,7 +59,11 @@ public class FluidGridHandler implements IFluidGridHandler {
             bucket.getCapability(CapabilityFluidHandler.FLUID_HANDLER_ITEM_CAPABILITY, null).ifPresent(fluidHandler -> {
                 network.getFluidStorageTracker().changed(player, stack.copy());
 
-                fluidHandler.fill(network.extractFluid(stack, FluidAttributes.BUCKET_VOLUME, Action.PERFORM), IFluidHandler.FluidAction.EXECUTE);
+                FluidStack extracted = network.extractFluid(stack, FluidAttributes.BUCKET_VOLUME, Action.PERFORM);
+
+                if (extracted != null) {
+                    fluidHandler.fill(extracted, IFluidHandler.FluidAction.EXECUTE);
+                }
 
                 if (shift) {
                     if (!player.inventory.addItemStackToInventory(fluidHandler.getContainer().copy())) {

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/grid/handler/ItemGridHandler.java

@@ -18,6 +18,7 @@ import net.minecraftforge.items.CapabilityItemHandler;
 import net.minecraftforge.items.IItemHandler;
 import net.minecraftforge.items.ItemHandlerHelper;
 
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.UUID;
 
@@ -107,6 +108,7 @@ public class ItemGridHandler implements IItemGridHandler {
     }
 
     @Override
+    @Nonnull
     public ItemStack onInsert(ServerPlayerEntity player, ItemStack stack) {
         if (!network.getSecurityManager().hasPermission(Permission.INSERT, player)) {
             return stack;
@@ -114,7 +116,7 @@ public class ItemGridHandler implements IItemGridHandler {
 
         network.getItemStorageTracker().changed(player, stack.copy());
 
-        ItemStack remainder = network.insertItem(stack, stack.getCount(), Action.PERFORM);
+        ItemStack remainder = StackUtils.nullToEmpty(network.insertItem(stack, stack.getCount(), Action.PERFORM));
 
         // TODO network.getNetworkItemHandler().drainEnergy(player, RS.INSTANCE.config.wirelessGridInsertUsage);
 
@@ -152,8 +154,9 @@ public class ItemGridHandler implements IItemGridHandler {
     }
 
     @Override
+    @Nonnull
     public ItemStack onShiftClick(ServerPlayerEntity player, ItemStack stack) {
-        return StackUtils.nullToEmpty(onInsert(player, stack));
+        return onInsert(player, stack);
     }
 
     @Override

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/grid/handler/PortableFluidGridHandler.java

@@ -73,7 +73,7 @@ public class PortableFluidGridHandler implements IFluidGridHandler {
     public ItemStack onInsert(ServerPlayerEntity player, ItemStack container) {
         Pair<ItemStack, FluidStack> result = StackUtils.getFluid(container, true);
 
-        if (!result.getValue().isEmpty() && portableGrid.getFluidStorage().insert(result.getValue(), result.getValue().getAmount(), Action.SIMULATE) == null) {
+        if (!result.getValue().isEmpty() && portableGrid.getFluidStorage().insert(result.getValue(), result.getValue().getAmount(), Action.SIMULATE).isEmpty()) {
             portableGrid.getFluidStorageTracker().changed(player, result.getValue().copy());
 
             result = StackUtils.getFluid(container, false);

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/grid/handler/PortableItemGridHandler.java

@@ -7,7 +7,6 @@ import com.raoulvdberge.refinedstorage.api.util.Action;
 import com.raoulvdberge.refinedstorage.api.util.IComparer;
 import com.raoulvdberge.refinedstorage.apiimpl.API;
 import com.raoulvdberge.refinedstorage.tile.grid.portable.IPortableGrid;
-import com.raoulvdberge.refinedstorage.util.StackUtils;
 import net.minecraft.entity.player.ServerPlayerEntity;
 import net.minecraft.item.ItemStack;
 import net.minecraft.util.Direction;
@@ -15,6 +14,7 @@ import net.minecraftforge.items.CapabilityItemHandler;
 import net.minecraftforge.items.IItemHandler;
 import net.minecraftforge.items.ItemHandlerHelper;
 
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.UUID;
 
@@ -80,7 +80,7 @@ public class PortableItemGridHandler implements IItemGridHandler {
 
         ItemStack took = portableGrid.getItemStorage().extract(item, size, IComparer.COMPARE_NBT, Action.SIMULATE);
 
-        if (took != null) {
+        if (!took.isEmpty()) {
             if ((flags & EXTRACT_SHIFT) == EXTRACT_SHIFT) {
                 IItemHandler playerInventory = player.getCapability(CapabilityItemHandler.ITEM_HANDLER_CAPABILITY, Direction.UP).orElse(null);
 
@@ -105,8 +105,8 @@ public class PortableItemGridHandler implements IItemGridHandler {
         }
     }
 
-    @Nullable
     @Override
+    @Nonnull
     public ItemStack onInsert(ServerPlayerEntity player, ItemStack stack) {
         if (portableGrid.getStorage() == null || !grid.isActive()) {
             return stack;
@@ -133,17 +133,18 @@ public class PortableItemGridHandler implements IItemGridHandler {
         portableGrid.getItemStorageTracker().changed(player, stack.copy());
 
         if (single) {
-            if (portableGrid.getItemStorage().insert(stack, size, Action.SIMULATE) == null) {
+            if (portableGrid.getItemStorage().insert(stack, size, Action.SIMULATE).isEmpty()) {
                 portableGrid.getItemStorage().insert(stack, size, Action.PERFORM);
 
                 stack.shrink(size);
 
+                // TODO ???
                 if (stack.getCount() == 0) {
                     player.inventory.setItemStack(ItemStack.EMPTY);
                 }
             }
         } else {
-            player.inventory.setItemStack(StackUtils.nullToEmpty(portableGrid.getItemStorage().insert(stack, size, Action.PERFORM)));
+            player.inventory.setItemStack(portableGrid.getItemStorage().insert(stack, size, Action.PERFORM));
         }
 
         player.updateHeldItem();
@@ -152,8 +153,9 @@ public class PortableItemGridHandler implements IItemGridHandler {
     }
 
     @Override
+    @Nonnull
     public ItemStack onShiftClick(ServerPlayerEntity player, ItemStack stack) {
-        return StackUtils.nullToEmpty(onInsert(player, stack));
+        return onInsert(player, stack);
     }
 
     @Override

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/node/diskdrive/DiskDriveNetworkNode.java

@@ -81,8 +81,8 @@ public class DiskDriveNetworkNode extends NetworkNode implements IStorageProvide
                     slot,
                     itemDisks,
                     fluidDisks,
-                    s -> new StorageDiskItemDriveWrapper(DiskDriveNetworkNode.this, s),
+                    s -> new ItemDriveWrapperStorageDisk(DiskDriveNetworkNode.this, s),
-                    s -> new StorageDiskFluidDriveWrapper(DiskDriveNetworkNode.this, s)
+                    s -> new FluidDriveWrapperStorageDisk(DiskDriveNetworkNode.this, s)
                 );
 
                 if (network != null) {

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/node/diskdrive/FluidDriveWrapperStorageDisk.java

@@ -15,12 +15,12 @@ import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.Collection;
 
-public class StorageDiskFluidDriveWrapper implements IStorageDisk<FluidStack> {
+public class FluidDriveWrapperStorageDisk implements IStorageDisk<FluidStack> {
     private DiskDriveNetworkNode diskDrive;
     private IStorageDisk<FluidStack> parent;
     private DiskDriveNetworkNode.DiskState lastState;
 
-    public StorageDiskFluidDriveWrapper(DiskDriveNetworkNode diskDrive, IStorageDisk<FluidStack> parent) {
+    public FluidDriveWrapperStorageDisk(DiskDriveNetworkNode diskDrive, IStorageDisk<FluidStack> parent) {
         this.diskDrive = diskDrive;
         this.parent = parent;
         this.setSettings(
@@ -54,7 +54,7 @@ public class StorageDiskFluidDriveWrapper implements IStorageDisk<FluidStack> {
     }
 
     @Override
-    @Nullable
+    @Nonnull
     public FluidStack insert(@Nonnull FluidStack stack, int size, Action action) {
         if (!IWhitelistBlacklist.acceptsFluid(diskDrive.getFluidFilters(), diskDrive.getWhitelistBlacklistMode(), diskDrive.getCompare(), stack)) {
             return StackUtils.copy(stack, size);
@@ -63,8 +63,8 @@ public class StorageDiskFluidDriveWrapper implements IStorageDisk<FluidStack> {
         return parent.insert(stack, size, action);
     }
 
-    @Nullable
     @Override
+    @Nonnull
     public FluidStack extract(@Nonnull FluidStack stack, int size, int flags, Action action) {
         return parent.extract(stack, size, flags, action);
     }

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/node/diskdrive/ItemDriveWrapperStorageDisk.java

@@ -15,12 +15,12 @@ import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.Collection;
 
-public class StorageDiskItemDriveWrapper implements IStorageDisk<ItemStack> {
+public class ItemDriveWrapperStorageDisk implements IStorageDisk<ItemStack> {
     private DiskDriveNetworkNode diskDrive;
     private IStorageDisk<ItemStack> parent;
     private DiskDriveNetworkNode.DiskState lastState;
 
-    public StorageDiskItemDriveWrapper(DiskDriveNetworkNode diskDrive, IStorageDisk<ItemStack> parent) {
+    public ItemDriveWrapperStorageDisk(DiskDriveNetworkNode diskDrive, IStorageDisk<ItemStack> parent) {
         this.diskDrive = diskDrive;
         this.parent = parent;
         this.setSettings(
@@ -54,7 +54,7 @@ public class StorageDiskItemDriveWrapper implements IStorageDisk<ItemStack> {
     }
 
     @Override
-    @Nullable
+    @Nonnull
     public ItemStack insert(@Nonnull ItemStack stack, int size, Action action) {
         if (!IWhitelistBlacklist.acceptsItem(diskDrive.getItemFilters(), diskDrive.getWhitelistBlacklistMode(), diskDrive.getCompare(), stack)) {
             return ItemHandlerHelper.copyStackWithSize(stack, size);
@@ -63,8 +63,8 @@ public class StorageDiskItemDriveWrapper implements IStorageDisk<ItemStack> {
         return parent.insert(stack, size, action);
     }
 
-    @Nullable
     @Override
+    @Nonnull
     public ItemStack extract(@Nonnull ItemStack stack, int size, int flags, Action action) {
         return parent.extract(stack, size, flags, action);
     }

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/node/diskmanipulator/NetworkNodeDiskManipulator.java

@@ -182,7 +182,7 @@ public class NetworkNodeDiskManipulator extends NetworkNode implements IComparab
             ItemStack stack = stacks.get(i);
 
             ItemStack extracted = storage.extract(stack, upgrades.getItemInteractCount(), compare, Action.PERFORM);
-            if (extracted == null) {
+            if (extracted.isEmpty()) {
                 continue;
             }
 
@@ -217,7 +217,7 @@ public class NetworkNodeDiskManipulator extends NetworkNode implements IComparab
             ItemStack stack = stacks.get(i);
 
             ItemStack extracted = storage.extract(stack, upgrades.getItemInteractCount(), compare, Action.SIMULATE);
-            if (extracted == null) {
+            if (extracted.isEmpty()) {
                 continue;
             }
 
@@ -267,7 +267,7 @@ public class NetworkNodeDiskManipulator extends NetworkNode implements IComparab
 
         ItemStack remainder = storage.insert(extracted, extracted.getCount(), Action.PERFORM);
 
-        if (remainder != null) {
+        if (!remainder.isEmpty()) {
             network.insertItem(remainder, remainder.getCount(), Action.PERFORM);
         }
     }
@@ -275,16 +275,16 @@ public class NetworkNodeDiskManipulator extends NetworkNode implements IComparab
     private void insertFluidIntoNetwork(IStorageDisk<FluidStack> storage, int slot) {
         List<FluidStack> stacks = new ArrayList<>(storage.getStacks());
 
-        FluidStack extracted = null;
+        FluidStack extracted = FluidStack.EMPTY;
         int i = 0;
 
-        while (extracted == null && stacks.size() > i) {
+        while (extracted.isEmpty() && stacks.size() > i) {
             FluidStack stack = stacks.get(i++);
 
             extracted = storage.extract(stack, upgrades.getItemInteractCount(), compare, Action.PERFORM);
         }
 
-        if (extracted == null) {
+        if (extracted.isEmpty()) {
             moveDriveToOutput(slot);
             return;
         }
@@ -316,7 +316,7 @@ public class NetworkNodeDiskManipulator extends NetworkNode implements IComparab
             FluidStack stack = stacks.get(i);
 
             FluidStack extracted = storage.extract(stack, upgrades.getItemInteractCount(), compare, Action.SIMULATE);
-            if (extracted == null) {
+            if (extracted.isEmpty()) {
                 continue;
             }
 
@@ -366,7 +366,7 @@ public class NetworkNodeDiskManipulator extends NetworkNode implements IComparab
 
         FluidStack remainder = storage.insert(extracted, extracted.getAmount(), Action.PERFORM);
 
-        if (remainder != null) {
+        if (!remainder.isEmpty()) {
             network.insertFluid(remainder, remainder.getAmount(), Action.PERFORM);
         }
     }

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/node/diskmanipulator/StorageDiskFluidManipulatorWrapper.java

@@ -66,7 +66,7 @@ public class StorageDiskFluidManipulatorWrapper implements IStorageDisk<FluidSta
     }
 
     @Override
-    @Nullable
+    @Nonnull
     public FluidStack insert(@Nonnull FluidStack stack, int size, Action action) {
         if (!IWhitelistBlacklist.acceptsFluid(diskManipulator.getFluidFilters(), diskManipulator.getWhitelistBlacklistMode(), diskManipulator.getCompare(), stack)) {
             return StackUtils.copy(stack, size);
@@ -76,10 +76,10 @@ public class StorageDiskFluidManipulatorWrapper implements IStorageDisk<FluidSta
     }
 
     @Override
-    @Nullable
+    @Nonnull
     public FluidStack extract(@Nonnull FluidStack stack, int size, int flags, Action action) {
         if (!IWhitelistBlacklist.acceptsFluid(diskManipulator.getFluidFilters(), diskManipulator.getWhitelistBlacklistMode(), diskManipulator.getCompare(), stack)) {
-            return null;
+            return FluidStack.EMPTY;
         }
 
         return parent.extract(stack, size, flags, action);

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/node/diskmanipulator/StorageDiskItemManipulatorWrapper.java

@@ -61,7 +61,7 @@ public class StorageDiskItemManipulatorWrapper implements IStorageDisk<ItemStack
     }
 
     @Override
-    @Nullable
+    @Nonnull
     public ItemStack insert(@Nonnull ItemStack stack, int size, Action action) {
         if (!IWhitelistBlacklist.acceptsItem(diskManipulator.getItemFilters(), diskManipulator.getWhitelistBlacklistMode(), diskManipulator.getCompare(), stack)) {
             return ItemHandlerHelper.copyStackWithSize(stack, size);
@@ -71,10 +71,10 @@ public class StorageDiskItemManipulatorWrapper implements IStorageDisk<ItemStack
     }
 
     @Override
-    @Nullable
+    @Nonnull
     public ItemStack extract(@Nonnull ItemStack stack, int size, int flags, Action action) {
         if (!IWhitelistBlacklist.acceptsItem(diskManipulator.getItemFilters(), diskManipulator.getWhitelistBlacklistMode(), diskManipulator.getCompare(), stack)) {
-            return null;
+            return ItemStack.EMPTY;
         }
 
         return parent.extract(stack, size, flags, action);

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/node/storage/FluidStorageNetworkNode.java

@@ -139,7 +139,7 @@ public class FluidStorageNetworkNode extends NetworkNode implements IStorageScre
             API.instance().getStorageDiskManager((ServerWorld) world).markForSaving();
         }
 
-        this.storage = new StorageDiskFluidStorageWrapper(this, disk);
+        this.storage = new FluidStorageWrapperStorageDisk(this, disk);
     }
 
     public void setStorageId(UUID id) {

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/node/storage/FluidStorageWrapperStorageDisk.java

@@ -15,11 +15,11 @@ import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.Collection;
 
-public class StorageDiskFluidStorageWrapper implements IStorageDisk<FluidStack> {
+public class FluidStorageWrapperStorageDisk implements IStorageDisk<FluidStack> {
     private FluidStorageNetworkNode storage;
     private IStorageDisk<FluidStack> parent;
 
-    public StorageDiskFluidStorageWrapper(FluidStorageNetworkNode storage, IStorageDisk<FluidStack> parent) {
+    public FluidStorageWrapperStorageDisk(FluidStorageNetworkNode storage, IStorageDisk<FluidStack> parent) {
         this.storage = storage;
         this.parent = parent;
         this.setSettings(null, storage);
@@ -41,7 +41,7 @@ public class StorageDiskFluidStorageWrapper implements IStorageDisk<FluidStack>
     }
 
     @Override
-    @Nullable
+    @Nonnull
     public FluidStack insert(@Nonnull FluidStack stack, int size, Action action) {
         if (!IWhitelistBlacklist.acceptsFluid(storage.getFilters(), storage.getWhitelistBlacklistMode(), storage.getCompare(), stack)) {
             return StackUtils.copy(stack, size);
@@ -50,8 +50,8 @@ public class StorageDiskFluidStorageWrapper implements IStorageDisk<FluidStack>
         return parent.insert(stack, size, action);
     }
 
-    @Nullable
     @Override
+    @Nonnull
     public FluidStack extract(@Nonnull FluidStack stack, int size, int flags, Action action) {
         return parent.extract(stack, size, flags, action);
     }

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/node/storage/ItemStorageWrapperStorageDisk.java

@@ -15,11 +15,11 @@ import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.Collection;
 
-public class StorageDiskItemStorageWrapper implements IStorageDisk<ItemStack> {
+public class ItemStorageWrapperStorageDisk implements IStorageDisk<ItemStack> {
     private StorageNetworkNode storage;
     private IStorageDisk<ItemStack> parent;
 
-    public StorageDiskItemStorageWrapper(StorageNetworkNode storage, IStorageDisk<ItemStack> parent) {
+    public ItemStorageWrapperStorageDisk(StorageNetworkNode storage, IStorageDisk<ItemStack> parent) {
         this.storage = storage;
         this.parent = parent;
         this.setSettings(null, storage);
@@ -41,7 +41,7 @@ public class StorageDiskItemStorageWrapper implements IStorageDisk<ItemStack> {
     }
 
     @Override
-    @Nullable
+    @Nonnull
     public ItemStack insert(@Nonnull ItemStack stack, int size, Action action) {
         if (!IWhitelistBlacklist.acceptsItem(storage.getFilters(), storage.getWhitelistBlacklistMode(), storage.getCompare(), stack)) {
             return ItemHandlerHelper.copyStackWithSize(stack, size);
@@ -50,8 +50,8 @@ public class StorageDiskItemStorageWrapper implements IStorageDisk<ItemStack> {
         return parent.insert(stack, size, action);
     }
 
-    @Nullable
     @Override
+    @Nonnull
     public ItemStack extract(@Nonnull ItemStack stack, int size, int flags, Action action) {
         return parent.extract(stack, size, flags, action);
     }

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/node/storage/StorageNetworkNode.java

@@ -139,7 +139,7 @@ public class StorageNetworkNode extends NetworkNode implements IStorageScreen, I
             API.instance().getStorageDiskManager((ServerWorld) world).markForSaving();
         }
 
-        this.storage = new StorageDiskItemStorageWrapper(this, disk);
+        this.storage = new ItemStorageWrapperStorageDisk(this, disk);
     }
 
     public void setStorageId(UUID id) {

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/storage/disk/FluidStorageDisk.java

@@ -67,8 +67,12 @@ public class FluidStorageDisk implements IStorageDisk<FluidStack> {
     }
 
     @Override
-    @Nullable
+    @Nonnull
     public FluidStack insert(@Nonnull FluidStack stack, int size, Action action) {
+        if (stack.isEmpty()) {
+            return stack;
+        }
+
         for (FluidStack otherStack : stacks.get(stack.getFluid())) {
             if (otherStack.isFluidEqual(stack)) {
                 if (getCapacity() != -1 && getStored() + size > getCapacity()) {
@@ -92,7 +96,7 @@ public class FluidStorageDisk implements IStorageDisk<FluidStack> {
                         onChanged();
                     }
 
-                    return null;
+                    return FluidStack.EMPTY;
                 }
             }
         }
@@ -118,13 +122,17 @@ public class FluidStorageDisk implements IStorageDisk<FluidStack> {
                 onChanged();
             }
 
-            return null;
+            return FluidStack.EMPTY;
         }
     }
 
     @Override
-    @Nullable
+    @Nonnull
     public FluidStack extract(@Nonnull FluidStack stack, int size, int flags, Action action) {
+        if (stack.isEmpty()) {
+            return stack;
+        }
+
         for (FluidStack otherStack : stacks.get(stack.getFluid())) {
             if (API.instance().getComparer().isEqual(otherStack, stack, flags)) {
                 if (size > otherStack.getAmount()) {
@@ -145,7 +153,7 @@ public class FluidStorageDisk implements IStorageDisk<FluidStack> {
             }
         }
 
-        return null;
+        return FluidStack.EMPTY;
     }
 
     @Override

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/storage/disk/ItemStorageDisk.java

@@ -73,8 +73,12 @@ public class ItemStorageDisk implements IStorageDisk<ItemStack> {
     }
 
     @Override
-    @Nullable
+    @Nonnull
     public ItemStack insert(@Nonnull ItemStack stack, int size, Action action) {
+        if (stack.isEmpty()) {
+            return stack;
+        }
+
         for (ItemStack otherStack : stacks.get(stack.getItem())) {
             if (API.instance().getComparer().isEqualNoQuantity(otherStack, stack)) {
                 if (getCapacity() != -1 && getStored() + size > getCapacity()) {
@@ -98,7 +102,7 @@ public class ItemStorageDisk implements IStorageDisk<ItemStack> {
                         onChanged();
                     }
 
-                    return null;
+                    return ItemStack.EMPTY;
                 }
             }
         }
@@ -124,13 +128,17 @@ public class ItemStorageDisk implements IStorageDisk<ItemStack> {
                 onChanged();
             }
 
-            return null;
+            return ItemStack.EMPTY;
         }
     }
 
     @Override
-    @Nullable
+    @Nonnull
     public ItemStack extract(@Nonnull ItemStack stack, int size, int flags, Action action) {
+        if (stack.isEmpty()) {
+            return stack;
+        }
+
         for (ItemStack otherStack : stacks.get(stack.getItem())) {
             if (API.instance().getComparer().isEqual(otherStack, stack, flags)) {
                 if (size > otherStack.getCount()) {
@@ -151,7 +159,7 @@ public class ItemStorageDisk implements IStorageDisk<ItemStack> {
             }
         }
 
-        return null;
+        return ItemStack.EMPTY;
     }
 
     @Override

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/storage/disk/PortableFluidStorageDisk.java

@@ -43,8 +43,8 @@ public class PortableFluidStorageDisk implements IStorageDisk<FluidStack> {
         return parent.getStacks();
     }
 
-    @Nullable
     @Override
+    @Nonnull
     public FluidStack insert(@Nonnull FluidStack stack, int size, Action action) {
         int storedPre = parent.getStored();
 
@@ -61,12 +61,12 @@ public class PortableFluidStorageDisk implements IStorageDisk<FluidStack> {
         return remainder;
     }
 
-    @Nullable
     @Override
+    @Nonnull
     public FluidStack extract(@Nonnull FluidStack stack, int size, int flags, Action action) {
         FluidStack extracted = parent.extract(stack, size, flags, action);
 
-        if (action == Action.PERFORM && extracted != null) {
+        if (action == Action.PERFORM && !extracted.isEmpty()) {
             portableGrid.getFluidCache().remove(extracted, extracted.getAmount(), false);
         }
 

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/storage/disk/PortableItemStorageDisk.java

@@ -43,8 +43,8 @@ public class PortableItemStorageDisk implements IStorageDisk<ItemStack> {
         return parent.getStacks();
     }
 
-    @Nullable
     @Override
+    @Nonnull
     public ItemStack insert(@Nonnull ItemStack stack, int size, Action action) {
         int storedPre = parent.getStored();
 
@@ -61,12 +61,12 @@ public class PortableItemStorageDisk implements IStorageDisk<ItemStack> {
         return remainder;
     }
 
-    @Nullable
     @Override
+    @Nonnull
     public ItemStack extract(@Nonnull ItemStack stack, int size, int flags, Action action) {
         ItemStack extracted = parent.extract(stack, size, flags, action);
 
-        if (action == Action.PERFORM && extracted != null) {
+        if (action == Action.PERFORM && !extracted.isEmpty()) {
             portableGrid.getItemCache().remove(extracted, extracted.getCount(), false);
         }
 

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/storage/externalstorage/FluidExternalStorage.java

@@ -76,14 +76,18 @@ public class FluidExternalStorage implements IExternalStorage<FluidStack> {
         return Collections.emptyList();
     }
 
-    @Nullable
     @Override
+    @Nonnull
     public FluidStack insert(@Nonnull FluidStack stack, int size, Action action) {
+        if (stack.isEmpty()) {
+            return stack;
+        }
+
         if (context.acceptsFluid(stack)) {
             int filled = handlerSupplier.get().fill(StackUtils.copy(stack, size), action == Action.PERFORM ? IFluidHandler.FluidAction.EXECUTE : IFluidHandler.FluidAction.SIMULATE);
 
             if (filled == size) {
-                return null;
+                return FluidStack.EMPTY;
             }
 
             return StackUtils.copy(stack, size - filled);
@@ -92,13 +96,17 @@ public class FluidExternalStorage implements IExternalStorage<FluidStack> {
         return StackUtils.copy(stack, size);
     }
 
-    @Nullable
     @Override
+    @Nonnull
     public FluidStack extract(@Nonnull FluidStack stack, int size, int flags, Action action) {
+        if (stack.isEmpty()) {
+            return stack;
+        }
+
         IFluidHandler handler = handlerSupplier.get();
 
         if (handler == null) {
-            return null;
+            return FluidStack.EMPTY;
         }
 
         return handler.drain(StackUtils.copy(stack, size), action == Action.PERFORM ? IFluidHandler.FluidAction.EXECUTE : IFluidHandler.FluidAction.SIMULATE);

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/storage/externalstorage/ItemExternalStorage.java

@@ -6,7 +6,6 @@ import com.raoulvdberge.refinedstorage.api.storage.externalstorage.IExternalStor
 import com.raoulvdberge.refinedstorage.api.storage.externalstorage.IExternalStorageContext;
 import com.raoulvdberge.refinedstorage.api.util.Action;
 import com.raoulvdberge.refinedstorage.apiimpl.API;
-import com.raoulvdberge.refinedstorage.util.StackUtils;
 import net.minecraft.item.ItemStack;
 import net.minecraftforge.items.IItemHandler;
 import net.minecraftforge.items.ItemHandlerHelper;
@@ -78,31 +77,39 @@ public class ItemExternalStorage implements IExternalStorage<ItemStack> {
         return stacks;
     }
 
-    @Nullable
     @Override
+    @Nonnull
     public ItemStack insert(@Nonnull ItemStack stack, int size, Action action) {
+        if (stack.isEmpty()) {
+            return stack;
+        }
+
         IItemHandler handler = handlerSupplier.get();
 
         if (handler != null && context.acceptsItem(stack)) {
-            return StackUtils.emptyToNull(ItemHandlerHelper.insertItem(handler, ItemHandlerHelper.copyStackWithSize(stack, size), action == Action.SIMULATE));
+            return ItemHandlerHelper.insertItem(handler, ItemHandlerHelper.copyStackWithSize(stack, size), action == Action.SIMULATE);
         }
 
         return ItemHandlerHelper.copyStackWithSize(stack, size);
     }
 
-    @Nullable
     @Override
+    @Nonnull
     public ItemStack extract(@Nonnull ItemStack stack, int size, int flags, Action action) {
-        int remaining = size;
+        if (stack.isEmpty()) {
-
+            return stack;
-        ItemStack received = null;
+        }
 
         IItemHandler handler = handlerSupplier.get();
 
         if (handler == null) {
-            return null;
+            return ItemStack.EMPTY;
         }
 
+        int remaining = size;
+
+        ItemStack received = ItemStack.EMPTY;
+
         for (int i = 0; i < handler.getSlots(); ++i) {
             ItemStack slot = handler.getStackInSlot(i);
 
@@ -110,7 +117,7 @@ public class ItemExternalStorage implements IExternalStorage<ItemStack> {
                 ItemStack got = handler.extractItem(i, remaining, action == Action.SIMULATE);
 
                 if (!got.isEmpty()) {
-                    if (received == null) {
+                    if (received.isEmpty()) {
                         received = got.copy();
                     } else {
                         received.grow(got.getCount());

src/main/java/com/raoulvdberge/refinedstorage/tile/ControllerTile.java

@@ -315,7 +315,7 @@ public class ControllerTile extends BaseTile implements ITickableTileEntity, INe
                 inserted += storage.getCacheDelta(storedPre, size, remainder);
             }
 
-            if (remainder == null) {
+            if (remainder.isEmpty()) {
                 // The external storage is responsible for sending changes, we don't need to anymore
                 if (storage instanceof IExternalStorage && action == Action.PERFORM) {
                     ((IExternalStorage) storage).update(this);
@@ -340,6 +340,11 @@ public class ControllerTile extends BaseTile implements ITickableTileEntity, INe
             itemStorage.add(stack, inserted - insertedExternally, false, false);
         }
 
+        // TODO Remove.
+        if (remainder.isEmpty()) {
+            remainder = null;
+        }
+
         return remainder;
     }
 
@@ -350,16 +355,16 @@ public class ControllerTile extends BaseTile implements ITickableTileEntity, INe
 
         int extractedExternally = 0;
 
-        ItemStack newStack = null;
+        ItemStack newStack = ItemStack.EMPTY;
 
         for (IStorage<ItemStack> storage : this.itemStorage.getStorages()) {
-            ItemStack took = null;
+            ItemStack took = ItemStack.EMPTY;
 
             if (filter.test(storage) && storage.getAccessType() != AccessType.INSERT) {
                 took = storage.extract(stack, requested - received, flags, action);
             }
 
-            if (took != null) {
+            if (!took.isEmpty()) {
                 // The external storage is responsible for sending changes, we don't need to anymore
                 if (storage instanceof IExternalStorage && action == Action.PERFORM) {
                     ((IExternalStorage) storage).update(this);
@@ -367,7 +372,7 @@ public class ControllerTile extends BaseTile implements ITickableTileEntity, INe
                     extractedExternally += took.getCount();
                 }
 
-                if (newStack == null) {
+                if (newStack.isEmpty()) {
                     newStack = took;
                 } else {
                     newStack.grow(took.getCount());
@@ -381,10 +386,15 @@ public class ControllerTile extends BaseTile implements ITickableTileEntity, INe
             }
         }
 
-        if (newStack != null && newStack.getCount() - extractedExternally > 0 && action == Action.PERFORM) {
+        if (newStack.getCount() - extractedExternally > 0 && action == Action.PERFORM) {
             itemStorage.remove(newStack, newStack.getCount() - extractedExternally, false);
         }
 
+        // TODO Remove.
+        if (newStack.isEmpty()) {
+            newStack = null;
+        }
+
         return newStack;
     }
 
@@ -413,7 +423,7 @@ public class ControllerTile extends BaseTile implements ITickableTileEntity, INe
                 inserted += storage.getCacheDelta(storedPre, size, remainder);
             }
 
-            if (remainder == null) {
+            if (remainder.isEmpty()) {
                 // The external storage is responsible for sending changes, we don't need to anymore
                 if (storage instanceof IExternalStorage && action == Action.PERFORM) {
                     ((IExternalStorage) storage).update(this);
@@ -438,6 +448,11 @@ public class ControllerTile extends BaseTile implements ITickableTileEntity, INe
             fluidStorage.add(stack, inserted - insertedExternally, false, false);
         }
 
+        // TODO Remove.
+        if (remainder.isEmpty()) {
+            remainder = null;
+        }
+
         return remainder;
     }
 
@@ -448,16 +463,16 @@ public class ControllerTile extends BaseTile implements ITickableTileEntity, INe
 
         int extractedExternally = 0;
 
-        FluidStack newStack = null;
+        FluidStack newStack = FluidStack.EMPTY;
 
         for (IStorage<FluidStack> storage : this.fluidStorage.getStorages()) {
-            FluidStack took = null;
+            FluidStack took = FluidStack.EMPTY;
 
             if (filter.test(storage) && storage.getAccessType() != AccessType.INSERT) {
                 took = storage.extract(stack, requested - received, flags, action);
             }
 
-            if (took != null) {
+            if (!took.isEmpty()) {
                 // The external storage is responsible for sending changes, we don't need to anymore
                 if (storage instanceof IExternalStorage && action == Action.PERFORM) {
                     ((IExternalStorage) storage).update(this);
@@ -465,7 +480,7 @@ public class ControllerTile extends BaseTile implements ITickableTileEntity, INe
                     extractedExternally += took.getAmount();
                 }
 
-                if (newStack == null) {
+                if (newStack.isEmpty()) {
                     newStack = took;
                 } else {
                     newStack.grow(took.getAmount());
@@ -479,10 +494,15 @@ public class ControllerTile extends BaseTile implements ITickableTileEntity, INe
             }
         }
 
-        if (newStack != null && newStack.getAmount() - extractedExternally > 0 && action == Action.PERFORM) {
+        if (newStack.getAmount() - extractedExternally > 0 && action == Action.PERFORM) {
             fluidStorage.remove(newStack, newStack.getAmount() - extractedExternally, false);
         }
 
+        // TODO Remove.
+        if (newStack.isEmpty()) {
+            newStack = null;
+        }
+
         return newStack;
     }