make array into immutable collection (spotbugs issue)

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1893860 13f79535-47bb-0310-9956-ffa450edef68

poi/src/main/java/org/apache/poi/hssf/eventusermodel/HSSFEventFactory.java

@@ -73,7 +73,7 @@ public class HSSFEventFactory {
         }
         // If in doubt, go for the default
         if (name == null) {
-            name = WORKBOOK_DIR_ENTRY_NAMES[0];
+            name = WORKBOOK_DIR_ENTRY_NAMES.get(0);
         }
 
         try (InputStream in = dir.createDocumentInputStream(name)) {

poi/src/main/java/org/apache/poi/hssf/extractor/OldExcelExtractor.java

@@ -152,7 +152,7 @@ public class OldExcelExtractor implements POITextExtractor {
             book = (DocumentNode)directory.getEntry(OLD_WORKBOOK_DIR_ENTRY_NAME);
         } catch (FileNotFoundException | IllegalArgumentException e) {
             // some files have "Workbook" instead
-            book = (DocumentNode)directory.getEntry(WORKBOOK_DIR_ENTRY_NAMES[0]);
+            book = (DocumentNode)directory.getEntry(WORKBOOK_DIR_ENTRY_NAMES.get(0));
         }
 
         if (book == null) {

poi/src/main/java/org/apache/poi/hssf/model/InternalWorkbook.java

@@ -20,10 +20,7 @@ package org.apache.poi.hssf.model;
 import static org.apache.logging.log4j.util.Unbox.box;
 
 import java.security.AccessControlException;
-import java.util.ArrayList;
-import java.util.LinkedHashMap;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 import java.util.Map.Entry;
 
 import org.apache.logging.log4j.LogManager;
@@ -92,12 +89,15 @@ public final class InternalWorkbook {
      *  "Workbook". However, some weird XLS generators use "WORKBOOK"
      *  or "BOOK".
      */
-    public static final String[] WORKBOOK_DIR_ENTRY_NAMES = {
-        "Workbook", // as per BIFF8 spec
-        "WORKBOOK", // Typically from third party programs
-        "BOOK",     // Typically odd Crystal Reports exports
-        "WorkBook", // Another third party program special
-    };
+    public static final List<String> WORKBOOK_DIR_ENTRY_NAMES = Collections.unmodifiableList(
+            Arrays.asList(
+                    "Workbook", // as per BIFF8 spec
+                    "WORKBOOK", // Typically from third party programs
+                    "BOOK",     // Typically odd Crystal Reports exports
+                    "WorkBook"  // Another third party program special
+            )
+    );
+
     /**
      * Name of older (pre-Excel 97) Workbook streams, which
      *  aren't supported by HSSFWorkbook, only by

poi/src/main/java/org/apache/poi/hssf/usermodel/HSSFWorkbook.java

@@ -1376,7 +1376,7 @@ public final class HSSFWorkbook extends POIDocument implements Workbook {
             // Don't write out the old Workbook, we'll be doing our new one
             // If the file had an "incorrect" name for the workbook stream,
             // don't write the old one as we'll use the correct name shortly
-            excepts.addAll(Arrays.asList(WORKBOOK_DIR_ENTRY_NAMES));
+            excepts.addAll(WORKBOOK_DIR_ENTRY_NAMES);
 
             // summary information has been already written via writeProperties and might go in a
             // different stream, if the file is cryptoapi encrypted