Stop anvil guis from giving out input items

v1_12_R1/src/main/java/net/citizensnpcs/nms/v1_12_R1/util/NMSImpl.java

@@ -865,6 +865,11 @@ public class NMSImpl implements NMSBridge {
                 handle) {
             private CraftInventoryView bukkitEntity;
 
+            @Override
+            protected void a(EntityHuman entityhuman, net.minecraft.server.v1_12_R1.World world,
+                    IInventory iinventory) {
+            }
+
             @Override
             public void e() {
                 super.e();

v1_13_R2/src/main/java/net/citizensnpcs/nms/v1_13_R2/util/NMSImpl.java

@@ -900,6 +900,11 @@ public class NMSImpl implements NMSBridge {
                 handle) {
             private CraftInventoryView bukkitEntity;
 
+            @Override
+            protected void a(EntityHuman entityhuman, net.minecraft.server.v1_13_R2.World world,
+                    IInventory iinventory) {
+            }
+
             @Override
             public void d() {
                 super.d();

v1_14_R1/src/main/java/net/citizensnpcs/nms/v1_14_R1/util/NMSImpl.java

@@ -969,6 +969,11 @@ public class NMSImpl implements NMSBridge {
         final ContainerAnvil container = new ContainerAnvil(handle.nextContainerCounter(), handle.inventory, access) {
             private CraftInventoryView bukkitEntity;
 
+            @Override
+            protected void a(EntityHuman entityhuman, net.minecraft.server.v1_14_R1.World world,
+                    IInventory iinventory) {
+            }
+
             @Override
             public void e() {
                 super.e();

v1_15_R1/src/main/java/net/citizensnpcs/nms/v1_15_R1/util/NMSImpl.java

@@ -981,6 +981,11 @@ public class NMSImpl implements NMSBridge {
         final ContainerAnvil container = new ContainerAnvil(handle.nextContainerCounter(), handle.inventory, access) {
             private CraftInventoryView bukkitEntity;
 
+            @Override
+            protected void a(EntityHuman entityhuman, net.minecraft.server.v1_15_R1.World world,
+                    IInventory iinventory) {
+            }
+
             @Override
             public void e() {
                 super.e();

v1_16_R3/src/main/java/net/citizensnpcs/nms/v1_16_R3/util/NMSImpl.java

@@ -1005,6 +1005,11 @@ public class NMSImpl implements NMSBridge {
                 ContainerAccess.at(handle.world, new BlockPosition(0, 0, 0))) {
             private CraftInventoryView bukkitEntity;
 
+            @Override
+            protected void a(EntityHuman entityhuman, net.minecraft.server.v1_16_R3.World world,
+                    IInventory iinventory) {
+            }
+
             @Override
             public void e() {
                 super.e();

v1_17_R1/src/main/java/net/citizensnpcs/nms/v1_17_R1/util/NMSImpl.java

@@ -1010,6 +1010,10 @@ public class NMSImpl implements NMSBridge {
                 ContainerLevelAccess.create(handle.level, new BlockPos(0, 0, 0))) {
             private CraftInventoryView bukkitEntity;
 
+            @Override
+            protected void clearContainer(net.minecraft.world.entity.player.Player entityhuman, Container iinventory) {
+            }
+
             @Override
             public void createResult() {
                 super.createResult();

v1_18_R2/src/main/java/net/citizensnpcs/nms/v1_18_R2/util/NMSImpl.java

@@ -1017,6 +1017,10 @@ public class NMSImpl implements NMSBridge {
                 ContainerLevelAccess.create(handle.level, new BlockPos(0, 0, 0))) {
             private CraftInventoryView bukkitEntity;
 
+            @Override
+            protected void clearContainer(net.minecraft.world.entity.player.Player entityhuman, Container iinventory) {
+            }
+
             @Override
             public void createResult() {
                 super.createResult();

v1_19_R1/src/main/java/net/citizensnpcs/nms/v1_19_R1/util/NMSImpl.java

@@ -1033,6 +1033,10 @@ public class NMSImpl implements NMSBridge {
                 ContainerLevelAccess.create(handle.level, new BlockPos(0, 0, 0))) {
             private CraftInventoryView bukkitEntity;
 
+            @Override
+            protected void clearContainer(net.minecraft.world.entity.player.Player entityhuman, Container iinventory) {
+            }
+
             @Override
             public void createResult() {
                 super.createResult();
@@ -1041,15 +1045,13 @@ public class NMSImpl implements NMSBridge {
 
             @Override
             public CraftInventoryView getBukkitView() {
-                if (this.bukkitEntity != null) {
+                if (this.bukkitEntity == null) {
-                    return this.bukkitEntity;
-                } else {
                     this.bukkitEntity = new CraftInventoryView(this.player.getBukkitEntity(),
                             new CitizensInventoryAnvil(this.access.getLocation(), this.inputSlots, this.resultSlots,
                                     this, anvil),
                             this);
-                    return this.bukkitEntity;
                 }
+                return this.bukkitEntity;
             }
         };
         container.getBukkitView().setItem(0, anvil.getItem(0));