Fix ArrayIndexOutOfBoundsException in XSSFTextParagraph when auto number scheme index is out of range

poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFTextParagraph.java

@@ -865,7 +865,14 @@ public ListAutoNumber getBulletAutoNumberScheme() {
         ParagraphPropertyFetcher<ListAutoNumber> fetcher = new ParagraphPropertyFetcher<ListAutoNumber>(getLevel()){
             public boolean fetch(CTTextParagraphProperties props){
                 if(props.isSetBuAutoNum() && props.getBuAutoNum().getType() != null) {
-                    setValue(ListAutoNumber.values()[props.getBuAutoNum().getType().intValue() - 1]);
+                    int typeIdx = props.getBuAutoNum().getType().intValue() - 1;
+                    ListAutoNumber[] values = ListAutoNumber.values();
+                    if (typeIdx >= 0 && typeIdx < values.length) {
+                        setValue(values[typeIdx]);
+                    } else {
+                        // Fallback handling: use the default format when the value is out of range
+                        setValue(ListAutoNumber.ARABIC_PLAIN);
+                    }
                     return true;
                 }
                 return false;

poi-ooxml/src/test/java/org/apache/poi/xssf/usermodel/TestXSSFTextParagraph.java

@@ -18,6 +18,12 @@ Licensed to the Apache Software Foundation (ASF) under one or more
 
 import static org.junit.jupiter.api.Assertions.*;
 
+import org.openxmlformats.schemas.drawingml.x2006.main.STTextAutonumberScheme;
+import org.openxmlformats.schemas.drawingml.x2006.main.CTTextParagraphProperties;
+import org.openxmlformats.schemas.drawingml.x2006.main.CTTextAutonumberBullet;
+import org.openxmlformats.schemas.drawingml.x2006.main.STTextAutonumberScheme;
+import org.openxmlformats.schemas.drawingml.x2006.main.CTTextParagraph;
+
 import java.awt.Color;
 import java.io.IOException;
 import java.util.List;
@@ -224,4 +230,35 @@ void testXSSFTextParagraph2() throws IOException {
             assertArrayEquals(run.getFontColorAsBytes(), run2.getFontColorAsBytes());
         }
     }
+
+    @Test
+    public void testBulletAutoNumberSchemeOutOfBounds() throws IOException{
+        try (XSSFWorkbook wb = new XSSFWorkbook()) {
+            XSSFSheet sheet = wb.createSheet();
+            XSSFDrawing drawing = sheet.createDrawingPatriarch();
+            XSSFTextBox shape = drawing.createTextbox(new XSSFClientAnchor(0, 0, 0, 0, 0, 0, 1, 1));
+
+            // Ensure the paragraph is created correctly
+            XSSFTextParagraph para = shape.addNewTextParagraph();
+
+            // 1. Obtain or create the underlying XML structure
+            CTTextParagraph ctPara = para.getXmlObject();
+            CTTextParagraphProperties pr = ctPara.isSetPPr() ? ctPara.getPPr() : ctPara.addNewPPr();
+
+            // 2. Force a level to avoid ParagraphPropertyFetcher errors
+            pr.setLvl(0);
+
+            // 3. Set an out-of-range autonumber type (e.g. 24)
+            CTTextAutonumberBullet bullet = pr.isSetBuAutoNum() ? pr.getBuAutoNum() : pr.addNewBuAutoNum();
+            bullet.setType(STTextAutonumberScheme.Enum.forInt(24));
+
+            // 4. Execute the test
+            // If you haven't applied the fix, this line will throw AIOOBE
+            // If the fix is applied, this should return ARABIC_PLAIN
+            ListAutoNumber result = para.getBulletAutoNumberScheme();
+
+            assertNotNull(result, "Result should not be null");
+            assertEquals(ListAutoNumber.ARABIC_PLAIN, result, "Should fallback to ARABIC_PLAIN for unknown index");
+        }
+    }
 }