implemented code review remarks

resolves DEVSIX-1398

Author: joris.schellekens

layout/src/main/java/com/itextpdf/layout/renderer/CollapsedTableBorders.java

@@ -73,52 +73,54 @@ protected CollapsedTableBorders collapseAllBordersAndEmptyRows() {
         CellRenderer[] currentRow;
         int[] rowspansToDeduct = new int[numberOfColumns];
         int numOfRowsToRemove = 0;
-        for (int row = startRow - largeTableIndexOffset; row <= finishRow - largeTableIndexOffset; row++) {
-            currentRow = rows.isEmpty() ? null : rows.get(row);
-            boolean hasCells = false;
-            for (int col = 0; col < numberOfColumns; col++) {
-                if (null != currentRow && null != currentRow[col]) {
-                    int colspan = (int) currentRow[col].getPropertyAsInteger(Property.COLSPAN);
-                    if (rowspansToDeduct[col] > 0) {
-                        int rowspan = (int) currentRow[col].getPropertyAsInteger(Property.ROWSPAN) - rowspansToDeduct[col];
-                        if (rowspan < 1) {
-                            Logger logger = LoggerFactory.getLogger(TableRenderer.class);
-                            logger.warn(LogMessageConstant.UNEXPECTED_BEHAVIOUR_DURING_TABLE_ROW_COLLAPSING);
-                            rowspan = 1;
+        if (!rows.isEmpty()) {
+            for (int row = startRow - largeTableIndexOffset; row <= finishRow - largeTableIndexOffset; row++) {
+                currentRow = rows.get(row);
+                boolean hasCells = false;
+                for (int col = 0; col < numberOfColumns; col++) {
+                    if (null != currentRow && null != currentRow[col]) {
+                        int colspan = (int) currentRow[col].getPropertyAsInteger(Property.COLSPAN);
+                        if (rowspansToDeduct[col] > 0) {
+                            int rowspan = (int) currentRow[col].getPropertyAsInteger(Property.ROWSPAN) - rowspansToDeduct[col];
+                            if (rowspan < 1) {
+                                Logger logger = LoggerFactory.getLogger(TableRenderer.class);
+                                logger.warn(LogMessageConstant.UNEXPECTED_BEHAVIOUR_DURING_TABLE_ROW_COLLAPSING);
+                                rowspan = 1;
+                            }
+                            currentRow[col].setProperty(Property.ROWSPAN, rowspan);
+                            if (0 != numOfRowsToRemove) {
+                                removeRows(row - numOfRowsToRemove, numOfRowsToRemove);
+                                row -= numOfRowsToRemove;
+                                numOfRowsToRemove = 0;
+                            }
                         }
-                        currentRow[col].setProperty(Property.ROWSPAN, rowspan);
-                        if (0 != numOfRowsToRemove) {
-                            removeRows(row - numOfRowsToRemove, numOfRowsToRemove);
-                            row -= numOfRowsToRemove;
-                            numOfRowsToRemove = 0;
+                        buildBordersArrays(currentRow[col], row, col, rowspansToDeduct);
+                        hasCells = true;
+                        for (int i = 0; i < colspan; i++) {
+                            rowspansToDeduct[col + i] = 0;
+                        }
+                        col += colspan - 1;
+                    } else {
+                        if (horizontalBorders.get(row).size() <= col) {
+                            horizontalBorders.get(row).add(null);
                         }
-                    }
-                    buildBordersArrays(currentRow[col], row, col, rowspansToDeduct);
-                    hasCells = true;
-                    for (int i = 0; i < colspan; i++) {
-                        rowspansToDeduct[col + i] = 0;
-                    }
-                    col += colspan - 1;
-                } else {
-                    if (horizontalBorders.get(row).size() <= col) {
-                        horizontalBorders.get(row).add(null);
                     }
                 }
-            }
-            if (!hasCells) {
-                if (row == rows.size() - 1) {
-                    removeRows(row - rowspansToDeduct[0], rowspansToDeduct[0]);
-                    // delete current row
-                    rows.remove(row - rowspansToDeduct[0]);
-                    setFinishRow(finishRow - 1);
-
-                    Logger logger = LoggerFactory.getLogger(TableRenderer.class);
-                    logger.warn(LogMessageConstant.LAST_ROW_IS_NOT_COMPLETE);
-                } else {
-                    for (int i = 0; i < numberOfColumns; i++) {
-                        rowspansToDeduct[i]++;
+                if (!hasCells) {
+                    if (row == rows.size() - 1) {
+                        removeRows(row - rowspansToDeduct[0], rowspansToDeduct[0]);
+                        // delete current row
+                        rows.remove(row - rowspansToDeduct[0]);
+                        setFinishRow(finishRow - 1);
+
+                        Logger logger = LoggerFactory.getLogger(TableRenderer.class);
+                        logger.warn(LogMessageConstant.LAST_ROW_IS_NOT_COMPLETE);
+                    } else {
+                        for (int i = 0; i < numberOfColumns; i++) {
+                            rowspansToDeduct[i]++;
+                        }
+                        numOfRowsToRemove++;
                     }
-                    numOfRowsToRemove++;
                 }
             }
         }