Additional work towards 1.16 compatibility

- Very basic implementation of the SideEffects system. Will definitely need fine tuning for it to be functional, but is not considered a priority in my opinion.
- Minor changes to the World interface and World implementations related to the SideEffects system. Shouldn't be the cause of any new bugs but be on the lookout.
- Included debug in BukkitImplLoader.java to assist contributors in understanding what needs to be implemented for the adapter to load properly.

Still very WIP but we're a few steps closer. So far, this is coming along better than I anticipated. Hopefully we can keep the momentum.

worldedit-core/src/main/java/com/sk89q/worldedit/command/GeneralCommands.java

@@ -49,10 +49,13 @@ import java.util.ArrayList;
 import com.sk89q.worldedit.extent.clipboard.Clipboard;
 import com.sk89q.worldedit.extension.platform.Capability;
 import com.sk89q.worldedit.function.mask.Mask;
+import com.sk89q.worldedit.util.SideEffect;
+import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.util.formatting.component.PaginationBox;
+import com.sk89q.worldedit.util.formatting.component.SideEffectBox;
+import com.sk89q.worldedit.util.formatting.text.Component;
 import com.sk89q.worldedit.util.formatting.text.TextComponent;
 import com.sk89q.worldedit.util.formatting.text.format.TextColor;
-import com.sk89q.worldedit.util.formatting.text.Component;
 import com.sk89q.worldedit.world.World;
 import com.sk89q.worldedit.world.item.ItemType;
 import java.io.FileNotFoundException;
@@ -142,24 +145,62 @@ public class GeneralCommands {
 
     @Command(
         name = "/fast",
-        desc = "Toggle fast mode"
+        desc = "Toggle fast mode side effects"
     )
     @CommandPermissions("worldedit.fast")
     public void fast(Actor actor, LocalSession session,
-                     @Arg(desc = "The new fast mode state", def = "")
-                        Boolean fastMode) {
-        boolean hasFastMode = session.hasFastMode();
-        if (fastMode != null && fastMode == hasFastMode) {
-            actor.printError(TranslatableComponent.of(fastMode ? "worldedit.fast.enabled.already" : "worldedit.fast.disabled.already"));
-            return;
+                    @Arg(desc = "The side effect", def = "")
+                        SideEffect sideEffect,
+                    @Arg(desc = "The new side effect state", def = "")
+                        SideEffect.State newState,
+                    @Switch(name = 'h', desc = "Show the info box")
+                        boolean showInfoBox) throws WorldEditException {
+        if (sideEffect != null) {
+            SideEffect.State currentState = session.getSideEffectSet().getState(sideEffect);
+            if (newState != null && newState == currentState) {
+                if (!showInfoBox) {
+                    actor.printError(TranslatableComponent.of(
+                            "worldedit.fast.sideeffect.already-set",
+                            TranslatableComponent.of(sideEffect.getDisplayName()),
+                            TranslatableComponent.of(newState.getDisplayName())
+                    ));
+                }
+                return;
+            }
+
+            if (newState != null) {
+                session.setSideEffectSet(session.getSideEffectSet().with(sideEffect, newState));
+                if (!showInfoBox) {
+                    actor.printInfo(TranslatableComponent.of(
+                            "worldedit.fast.sideeffect.set",
+                            TranslatableComponent.of(sideEffect.getDisplayName()),
+                            TranslatableComponent.of(newState.getDisplayName())
+                    ));
+                }
+            } else {
+                actor.printInfo(TranslatableComponent.of(
+                        "worldedit.fast.sideeffect.get",
+                        TranslatableComponent.of(sideEffect.getDisplayName()),
+                        TranslatableComponent.of(currentState.getDisplayName())
+                ));
+            }
+        } else if (newState != null) {
+            SideEffectSet applier = session.getSideEffectSet();
+            for (SideEffect sideEffectEntry : SideEffect.values()) {
+                applier = applier.with(sideEffectEntry, newState);
+            }
+            session.setSideEffectSet(applier);
+            if (!showInfoBox) {
+                actor.printInfo(TranslatableComponent.of(
+                        "worldedit.fast.sideeffect.set-all",
+                        TranslatableComponent.of(newState.getDisplayName())
+                ));
+            }
         }
 
-        if (hasFastMode) {
-            session.setFastMode(false);
-            actor.printInfo(TranslatableComponent.of("worldedit.fast.disabled"));
-        } else {
-            session.setFastMode(true);
-            actor.printInfo(TranslatableComponent.of("worldedit.fast.enabled"));
+        if (sideEffect == null || showInfoBox) {
+            SideEffectBox sideEffectBox = new SideEffectBox(session.getSideEffectSet());
+            actor.print(sideEffectBox.create(1));
         }
     }
 

worldedit-core/src/main/java/com/sk89q/worldedit/command/argument/EnumConverter.java

@@ -23,6 +23,7 @@ import com.boydti.fawe.object.brush.scroll.Scroll;
 import com.google.common.collect.ImmutableSet;
 import com.sk89q.worldedit.EditSession;
 import com.sk89q.worldedit.command.util.HookMode;
+import com.sk89q.worldedit.util.SideEffect;
 import com.sk89q.worldedit.util.TreeGenerator;
 import org.enginehub.piston.CommandManager;
 import org.enginehub.piston.converter.ArgumentConverter;
@@ -30,6 +31,7 @@ import org.enginehub.piston.converter.MultiKeyConverter;
 import org.enginehub.piston.inject.Key;
 
 import javax.annotation.Nullable;
+
 import java.util.EnumSet;
 import java.util.Locale;
 import java.util.Set;
@@ -48,6 +50,11 @@ public final class EnumConverter {
             full(EditSession.ReorderMode.class,
                 r -> ImmutableSet.of(r.getDisplayName()),
                 null));
+        commandManager.registerConverter(Key.of(SideEffect.State.class),
+                MultiKeyConverter.from(
+                    EnumSet.of(SideEffect.State.OFF, SideEffect.State.ON),
+                    r -> ImmutableSet.of(r.name().toLowerCase(Locale.US)),
+                    null));
         commandManager.registerConverter(Key.of(HookMode.class),
             basic(HookMode.class));
         commandManager.registerConverter(Key.of(Scroll.Action.class),

worldedit-core/src/main/java/com/sk89q/worldedit/command/argument/SideEffectConverter.java

@@ -0,0 +1,75 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.command.argument;
+
+import static org.enginehub.piston.converter.SuggestionHelper.limitByPrefix;
+
+import com.google.common.collect.ImmutableList;
+import com.sk89q.worldedit.WorldEdit;
+import com.sk89q.worldedit.command.util.EntityRemover;
+import com.sk89q.worldedit.util.SideEffect;
+import com.sk89q.worldedit.util.formatting.text.Component;
+import com.sk89q.worldedit.util.formatting.text.TextComponent;
+import org.enginehub.piston.CommandManager;
+import org.enginehub.piston.converter.ArgumentConverter;
+import org.enginehub.piston.converter.ConversionResult;
+import org.enginehub.piston.converter.FailedConversion;
+import org.enginehub.piston.converter.SuccessfulConversion;
+import org.enginehub.piston.inject.InjectedValueAccess;
+import org.enginehub.piston.inject.Key;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Locale;
+
+public class SideEffectConverter implements ArgumentConverter<SideEffect> {
+
+    public static void register(CommandManager commandManager) {
+        commandManager.registerConverter(Key.of(SideEffect.class), new SideEffectConverter());
+    }
+
+    private final TextComponent choices = TextComponent.of("any side effect");
+
+    private SideEffectConverter() {
+    }
+
+    private Collection<SideEffect> getSideEffects() {
+        return WorldEdit.getInstance().getPlatformManager().getSupportedSideEffects();
+    }
+
+    @Override
+    public Component describeAcceptableArguments() {
+        return choices;
+    }
+
+    @Override
+    public List<String> getSuggestions(String input, InjectedValueAccess context) {
+        return limitByPrefix(getSideEffects().stream().map(sideEffect -> sideEffect.name().toLowerCase(Locale.US)), input);
+    }
+
+    @Override
+    public ConversionResult<SideEffect> convert(String argument, InjectedValueAccess context) {
+        try {
+            return SuccessfulConversion.fromSingle(SideEffect.valueOf(argument.toUpperCase(Locale.US)));
+        } catch (Exception e) {
+            return FailedConversion.from(e);
+        }
+    }
+}