Bug 50319: Make row groups which include row 0 work

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1705844 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/hssf/record/aggregates/RowRecordsAggregate.java

@@ -293,7 +293,7 @@ public final class RowRecordsAggregate extends RecordAggregate {
 		RowRecord rowRecord = this.getRow( row );
 		int level = rowRecord.getOutlineLevel();
 		int currentRow = row;
-		while (this.getRow( currentRow ) != null) {
+		while (currentRow >= 0 && this.getRow( currentRow ) != null) {
 			rowRecord = this.getRow( currentRow );
 			if (rowRecord.getOutlineLevel() < level) {
 				return currentRow + 1;

src/testcases/org/apache/poi/ss/usermodel/BaseTestBugzillaIssues.java

@@ -1274,4 +1274,18 @@ public abstract class BaseTestBugzillaIssues {
 
         wb.close();
     }
+
+    @Test
+    public void test50319() throws IOException {
+        Workbook wb = new HSSFWorkbook();
+        Sheet sheet = wb.createSheet("Test");
+        sheet.createRow(0);
+        sheet.groupRow(0, 0);
+        sheet.setRowGroupCollapsed(0, true);
+        
+        sheet.groupColumn(0, 0);
+        sheet.setColumnGroupCollapsed(0, true);
+        
+        wb.close();
+    }
 }