Fix import order disagreement (kotlinx)

For checkstyle, 'kotlinx' is not specified, meaning it is expected
at the end, in alphabetical order with all other imports which lack
a defined ordering.

This disagrees with google-java-formatter and all IDE code formatter
configurations in use. This leads to confusion, manual correction or
in many cases ignored checkstyle warnings. This is in part due to
unhelpful checkstyle output:

Given:

    import kotlin.Pair;

    import kotlinx.coroutines.CoroutineDispatcher;

    import java.util.ArrayList;
    import java.util.Arrays;

Checkstyle reports:

    .../Foo.java:16:1: Wrong order for java.util.ArrayList import. Use
    Ctrl+Shift+O (Eclipse) or Ctrl+Alt+O (Intellij) to sort imports.
    https://source.android.com/setup/code-style#order-import-statements

Bug: 333533940
Test: manual
Change-Id: Ife87e1f92bdc620031cf2e90add6b688aef8b5ef
diff --git a/default-treewalker-checks.xml b/default-treewalker-checks.xml
index 4c75318..9a58e5f 100644
--- a/default-treewalker-checks.xml
+++ b/default-treewalker-checks.xml
@@ -154,12 +154,12 @@
 <module name="ImportOrder">
   <property name="severity" value="error"/>
   <message key="import.ordering" value="Wrong order for {0} import. Use Ctrl+Shift+O (Eclipse) or Ctrl+Alt+O (Intellij) to sort imports. https://source.android.com/setup/code-style#order-import-statements"/>
-  <property name="groups" value="android, androidx, com.android, dalvik, com, dagger, gov, io, junit, junitparams, libcore, net, kotlin, org, perfetto, vendor, java, javax"/>
+  <property name="groups" value="android, androidx, com.android, dalvik, com, dagger, gov, io, junit, junitparams, libcore, net, kotlin, kotlinx, org, perfetto, vendor, java, javax"/>
   <property name="ordered" value="true"/>
   <property name="option" value="top"/>
   <property name="separated" value="true"/>
   <property name="separatedStaticGroups" value="true"/>
-  <property name="staticGroups" value="android, androidx, com.android, dalvik, com, dagger, gov, io, junit, junitparams, libcore, net, kotlin, org, perfetto, java, javax"/>
+  <property name="staticGroups" value="android, androidx, com.android, dalvik, com, dagger, gov, io, junit, junitparams, libcore, net, kotlin, kotlinx, org, perfetto, java, javax"/>
 </module>
 <module name="Indentation">
   <property name="severity" value="error"/>