fixes from review

Author: me4502

worldedit-core/src/main/java/com/sk89q/worldedit/extension/factory/parser/mask/FullCubeMaskParser.java

@@ -19,7 +19,6 @@
 
 package com.sk89q.worldedit.extension.factory.parser.mask;
 
-import com.google.common.collect.ImmutableList;
 import com.sk89q.worldedit.WorldEdit;
 import com.sk89q.worldedit.extension.input.InputParseException;
 import com.sk89q.worldedit.extension.input.ParserContext;
@@ -31,7 +30,7 @@
 
 public class FullCubeMaskParser extends SimpleInputParser<Mask> {
 
-    private final List<String> aliases = ImmutableList.of("#fullcube");
+    private static final List<String> aliases = List.of("#fullcube");
 
     public FullCubeMaskParser(WorldEdit worldEdit) {
         super(worldEdit);

worldedit-core/src/main/java/com/sk89q/worldedit/function/mask/FullCubeMask.java

@@ -23,7 +23,7 @@
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.world.block.BlockState;
 
-public class FullCubeMask extends AbstractExtentMask {
+public final class FullCubeMask extends AbstractExtentMask {
 
     public FullCubeMask(Extent extent) {
         super(extent);