Add checkstyle validation for formatting, fix issues

config/checkstyle/checkstyle.xml

@@ -53,5 +53,13 @@
     <!-- <module name="PackageName"/> Unlikely that we would miss this in a PR -->
     <module name="ParameterName"/>
     <!-- <module name="TypeName"/> Unlikely that we would miss this in a PR -->
+    <!-- Validate assignment operators -->
+    <module name="WhitespaceAround">
+      <property name="tokens" value="ASSIGN"/>
+    </module>
+  </module>
+  <!-- Validate that command annotations are formatted correctly -->
+  <module name="RegexpMultiline">
+    <property name="format" value="^( +)@(Arg|Switch|Command)\(.*?\n\1 {5,}"/>
   </module>
 </module>

worldedit-core/src/legacy/java/com/sk89q/worldedit/blocks/MobSpawnerBlock.java

@@ -208,7 +208,7 @@ public class MobSpawnerBlock extends BaseBlock {
             this.spawnCount = spawnCountTag.getValue();
         }
         if (spawnRangeTag != null) {
-            this.spawnRange =spawnRangeTag.getValue();
+            this.spawnRange = spawnRangeTag.getValue();
         }
         if (minSpawnDelayTag != null) {
             this.minSpawnDelay = minSpawnDelayTag.getValue();

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

@@ -19,8 +19,6 @@
 
 package com.sk89q.worldedit.command;
 
-import static com.sk89q.worldedit.command.util.Logging.LogMode.REGION;
-
 import com.sk89q.worldedit.EditSession;
 import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.WorldEdit;
@@ -59,6 +57,8 @@ import java.util.Objects;
 import java.util.Set;
 import java.util.stream.Collectors;
 
+import static com.sk89q.worldedit.command.util.Logging.LogMode.REGION;
+
 /**
  * Implements biome-related commands such as "/biomelist".
  */
@@ -97,9 +97,9 @@ public class BiomeCommands {
     )
     @CommandPermissions("worldedit.biome.info")
     public void biomeInfo(Player player, LocalSession session,
-                          @Switch(name = 't', desc="Use the block you are looking at.")
+                          @Switch(name = 't', desc = "Use the block you are looking at.")
                               boolean useLineOfSight,
-                          @Switch(name = 'p', desc="Use the block you are currently in.")
+                          @Switch(name = 'p', desc = "Use the block you are currently in.")
                               boolean usePosition) throws WorldEditException {
         BiomeRegistry biomeRegistry = WorldEdit.getInstance().getPlatformManager()
                 .queryCapability(Capability.GAME_HOOKS).getRegistries().getBiomeRegistry();