Closer isn't available in the Guava version that Bukkit bundles.

src/main/java/com/sk89q/worldedit/command/SchematicCommands.java

@@ -19,7 +19,6 @@
 
 package com.sk89q.worldedit.command;
 
-import com.google.common.io.Closer;
 import com.sk89q.minecraft.util.commands.Command;
 import com.sk89q.minecraft.util.commands.CommandContext;
 import com.sk89q.minecraft.util.commands.CommandException;
@@ -41,6 +40,7 @@ import com.sk89q.worldedit.extent.clipboard.io.ClipboardWriter;
 import com.sk89q.worldedit.function.operation.Operations;
 import com.sk89q.worldedit.math.transform.Transform;
 import com.sk89q.worldedit.session.ClipboardHolder;
+import com.sk89q.worldedit.util.io.Closer;
 import com.sk89q.worldedit.util.command.parametric.Optional;
 import com.sk89q.worldedit.world.registry.WorldData;
 

src/main/java/com/sk89q/worldedit/util/io/Closer.java

@@ -0,0 +1,233 @@
+/*
+ * 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.util.io;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Throwables;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.lang.reflect.Method;
+import java.util.ArrayDeque;
+import java.util.Deque;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+public final class Closer implements Closeable {
+
+    private static final Logger logger = Logger.getLogger(Closer.class.getCanonicalName());
+
+    /**
+     * The suppressor implementation to use for the current Java version.
+     */
+    private static final Suppressor SUPPRESSOR = SuppressingSuppressor.isAvailable()
+            ? SuppressingSuppressor.INSTANCE
+            : LoggingSuppressor.INSTANCE;
+
+    /**
+     * Creates a new {@link Closer}.
+     */
+    public static Closer create() {
+        return new Closer(SUPPRESSOR);
+    }
+
+    @VisibleForTesting
+    final Suppressor suppressor;
+
+    // only need space for 2 elements in most cases, so try to use the smallest array possible
+    private final Deque<Closeable> stack = new ArrayDeque<Closeable>(4);
+    private Throwable thrown;
+
+    @VisibleForTesting Closer(Suppressor suppressor) {
+        this.suppressor = checkNotNull(suppressor); // checkNotNull to satisfy null tests
+    }
+
+    /**
+     * Registers the given {@code closeable} to be closed when this {@code Closer} is
+     * {@linkplain #close closed}.
+     *
+     * @return the given {@code closeable}
+     */
+    // close. this word no longer has any meaning to me.
+    public <C extends Closeable> C register(C closeable) {
+        stack.push(closeable);
+        return closeable;
+    }
+
+    /**
+     * Stores the given throwable and rethrows it. It will be rethrown as is if it is an
+     * {@code IOException}, {@code RuntimeException} or {@code Error}. Otherwise, it will be rethrown
+     * wrapped in a {@code RuntimeException}. <b>Note:</b> Be sure to declare all of the checked
+     * exception types your try block can throw when calling an overload of this method so as to avoid
+     * losing the original exception type.
+     *
+     * <p>This method always throws, and as such should be called as
+     * {@code throw closer.rethrow(e);} to ensure the compiler knows that it will throw.
+     *
+     * @return this method does not return; it always throws
+     * @throws IOException when the given throwable is an IOException
+     */
+    public RuntimeException rethrow(Throwable e) throws IOException {
+        thrown = e;
+        Throwables.propagateIfPossible(e, IOException.class);
+        throw Throwables.propagate(e);
+    }
+
+    /**
+     * Stores the given throwable and rethrows it. It will be rethrown as is if it is an
+     * {@code IOException}, {@code RuntimeException}, {@code Error} or a checked exception of the
+     * given type. Otherwise, it will be rethrown wrapped in a {@code RuntimeException}. <b>Note:</b>
+     * Be sure to declare all of the checked exception types your try block can throw when calling an
+     * overload of this method so as to avoid losing the original exception type.
+     *
+     * <p>This method always throws, and as such should be called as
+     * {@code throw closer.rethrow(e, ...);} to ensure the compiler knows that it will throw.
+     *
+     * @return this method does not return; it always throws
+     * @throws IOException when the given throwable is an IOException
+     * @throws X when the given throwable is of the declared type X
+     */
+    public <X extends Exception> RuntimeException rethrow(Throwable e,
+                                                          Class<X> declaredType) throws IOException, X {
+        thrown = e;
+        Throwables.propagateIfPossible(e, IOException.class);
+        Throwables.propagateIfPossible(e, declaredType);
+        throw Throwables.propagate(e);
+    }
+
+    /**
+     * Stores the given throwable and rethrows it. It will be rethrown as is if it is an
+     * {@code IOException}, {@code RuntimeException}, {@code Error} or a checked exception of either
+     * of the given types. Otherwise, it will be rethrown wrapped in a {@code RuntimeException}.
+     * <b>Note:</b> Be sure to declare all of the checked exception types your try block can throw
+     * when calling an overload of this method so as to avoid losing the original exception type.
+     *
+     * <p>This method always throws, and as such should be called as
+     * {@code throw closer.rethrow(e, ...);} to ensure the compiler knows that it will throw.
+     *
+     * @return this method does not return; it always throws
+     * @throws IOException when the given throwable is an IOException
+     * @throws X1 when the given throwable is of the declared type X1
+     * @throws X2 when the given throwable is of the declared type X2
+     */
+    public <X1 extends Exception, X2 extends Exception> RuntimeException rethrow(
+            Throwable e, Class<X1> declaredType1, Class<X2> declaredType2) throws IOException, X1, X2 {
+        thrown = e;
+        Throwables.propagateIfPossible(e, IOException.class);
+        Throwables.propagateIfPossible(e, declaredType1, declaredType2);
+        throw Throwables.propagate(e);
+    }
+
+    /**
+     * Closes all {@code Closeable} instances that have been added to this {@code Closer}. If an
+     * exception was thrown in the try block and passed to one of the {@code exceptionThrown} methods,
+     * any exceptions thrown when attempting to close a closeable will be suppressed. Otherwise, the
+     * <i>first</i> exception to be thrown from an attempt to close a closeable will be thrown and any
+     * additional exceptions that are thrown after that will be suppressed.
+     */
+    @Override
+    public void close() throws IOException {
+        Throwable throwable = thrown;
+
+        // close closeables in LIFO order
+        while (!stack.isEmpty()) {
+            Closeable closeable = stack.pop();
+            try {
+                closeable.close();
+            } catch (Throwable e) {
+                if (throwable == null) {
+                    throwable = e;
+                } else {
+                    suppressor.suppress(closeable, throwable, e);
+                }
+            }
+        }
+
+        if (thrown == null && throwable != null) {
+            Throwables.propagateIfPossible(throwable, IOException.class);
+            throw new AssertionError(throwable); // not possible
+        }
+    }
+
+    /**
+     * Suppression strategy interface.
+     */
+    @VisibleForTesting interface Suppressor {
+        /**
+         * Suppresses the given exception ({@code suppressed}) which was thrown when attempting to close
+         * the given closeable. {@code thrown} is the exception that is actually being thrown from the
+         * method. Implementations of this method should not throw under any circumstances.
+         */
+        void suppress(Closeable closeable, Throwable thrown, Throwable suppressed);
+    }
+
+    /**
+     * Suppresses exceptions by logging them.
+     */
+    @VisibleForTesting static final class LoggingSuppressor implements Suppressor {
+
+        static final LoggingSuppressor INSTANCE = new LoggingSuppressor();
+
+        @Override
+        public void suppress(Closeable closeable, Throwable thrown, Throwable suppressed) {
+            // log to the same place as Closeables
+            logger.log(Level.WARNING, "Suppressing exception thrown when closing " + closeable, suppressed);
+        }
+    }
+
+    /**
+     * Suppresses exceptions by adding them to the exception that will be thrown using JDK7's
+     * addSuppressed(Throwable) mechanism.
+     */
+    @VisibleForTesting static final class SuppressingSuppressor implements Suppressor {
+
+        static final SuppressingSuppressor INSTANCE = new SuppressingSuppressor();
+
+        static boolean isAvailable() {
+            return addSuppressed != null;
+        }
+
+        static final Method addSuppressed = getAddSuppressed();
+
+        private static Method getAddSuppressed() {
+            try {
+                return Throwable.class.getMethod("addSuppressed", Throwable.class);
+            } catch (Throwable e) {
+                return null;
+            }
+        }
+
+        @Override
+        public void suppress(Closeable closeable, Throwable thrown, Throwable suppressed) {
+            // ensure no exceptions from addSuppressed
+            if (thrown == suppressed) {
+                return;
+            }
+            try {
+                addSuppressed.invoke(thrown, suppressed);
+            } catch (Throwable e) {
+                // if, somehow, IllegalAccessException or another exception is thrown, fall back to logging
+                LoggingSuppressor.INSTANCE.suppress(closeable, thrown, suppressed);
+            }
+        }
+    }
+}