LUCENE-9785: Hunspell: don't check case in compound middle and end (#2398)

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

@@ -160,6 +160,7 @@ public class Hunspell {
   private Root<CharsRef> findStem(
       char[] wordChars, int offset, int length, WordCase originalCase, WordContext context) {
     checkCanceled.run();
+    boolean checkCase = context != COMPOUND_MIDDLE && context != COMPOUND_END;
     @SuppressWarnings({"rawtypes", "unchecked"})
     Root<CharsRef>[] result = new Root[1];
     stemmer.doStem(
@@ -168,7 +169,7 @@ public class Hunspell {
         length,
         context,
         (stem, formID, morphDataId) -> {
-          if (!acceptCase(originalCase, formID, stem)) {
+          if (checkCase && !acceptCase(originalCase, formID, stem)) {
             return dictionary.hasFlag(formID, Dictionary.HIDDEN_FLAG);
           }
           if (acceptsStem(formID)) {

lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/keepcase.aff

@@ -4,3 +4,5 @@ KEEPCASE Z
 
 SFX X Y 1
 SFX X 0 s . +s
+
+COMPOUNDFLAG C

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

@@ -1,4 +1,4 @@
-9
+11
 drink/X
 walk/XZ
 test/Z
@@ -8,3 +8,6 @@ baz./Z
 Quux./Z
 way/X
 ways/Z
+tvv/ZC
+school/C
+uni/ZC

lucene/analysis/common/src/test/org/apache/lucene/analysis/hunspell/keepcase.good

@@ -5,4 +5,8 @@ Quux.
 way
 Way
 WAY
-ways
+ways
+schooltvv
+Schooltvv
+SCHOOLTVV
+unitvv

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

@@ -6,4 +6,6 @@ baz.
 baz.
 Quux.
 Quux.
-Way
+Way
+unitvv, Uni tvv, uni
+unitvv, UNI TVV, uni

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

@@ -7,3 +7,5 @@ BAZ.
 quux.
 QUUX.
 Ways
+Unitvv
+UNITVV