LUCENE-9784: Hunspell suggestions: use US keyboard in absence of KEY option (#2389)

lucene/analysis/common/src/java/org/apache/lucene/analysis/hunspell/Dictionary.java

@@ -161,7 +161,7 @@ public class Dictionary {
   private char[] ignore;
 
   String tryChars = "";
-  String[] neighborKeyGroups = new String[0];
+  String[] neighborKeyGroups = {"qwertyuiop", "asdfghjkl", "zxcvbnm"};
   boolean enableSplitSuggestions = true;
   List<RepEntry> repTable = new ArrayList<>();
   List<List<String>> mapTable = new ArrayList<>();

lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/TestSpellChecking.java

@@ -212,6 +212,10 @@ public class TestSpellChecking extends StemmerTestBase {
     doTest("nosuggest");
   }
 
+  public void testUseUSKeyboardAsDefaultKeyValue() throws Exception {
+    doTest("keyDefault");
+  }
+
   protected void doTest(String name) throws Exception {
     checkSpellCheckerExpectations(
         Path.of(getClass().getResource(name + ".aff").toURI()).getParent().resolve(name));

lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/keyDefault.dic

@@ -0,0 +1,3 @@
+2
+gab
+an

lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/keyDefault.sug

@@ -0,0 +1 @@
+gab, an

lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/keyDefault.wrong

@@ -0,0 +1 @@
+gan