Fix SO exception by adjusting causeOfNothing field provided by paragraph renderer

DEVSIX-7293

Author: introfog

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

@@ -323,7 +323,9 @@ protected LayoutResult directLayout(LayoutContext layoutContext) {
                     boolean keepTogether = isKeepTogether(result.getCauseOfNothing());
                     if (keepTogether) {
                         floatRendererAreas.retainAll(nonChildFloatingRendererAreas);
-                        return new MinMaxWidthLayoutResult(LayoutResult.NOTHING, null, null, this, null == result.getCauseOfNothing() ? this : result.getCauseOfNothing());
+                        // Use paragraph as a cause of nothing because parent relationship between TextRenderer
+                        // and ParagraphRenderer can be broken by ParagraphRenderer#updateParentLines method.
+                        return new MinMaxWidthLayoutResult(LayoutResult.NOTHING, null, null, this, this);
                     } else {
                         if (marginsCollapsingEnabled) {
                             if (anythingPlaced && notAllKidsAreFloats) {

layout/src/test/java/com/itextpdf/layout/TableTest.java

@@ -57,6 +57,7 @@ This file is part of the iText (R) project.
 import com.itextpdf.layout.properties.VerticalAlignment;
 import com.itextpdf.layout.renderer.DocumentRenderer;
 import com.itextpdf.layout.renderer.TableRenderer;
+import com.itextpdf.test.LogLevelConstants;
 import com.itextpdf.test.annotations.LogMessage;
 import com.itextpdf.test.annotations.LogMessages;
 import com.itextpdf.test.annotations.type.IntegrationTest;
@@ -3521,6 +3522,41 @@ public void tableRelayoutTest() {
         }
     }
 
+    @Test
+    @LogMessages(messages = {
+            @LogMessage(messageTemplate = LayoutLogMessageConstant.ELEMENT_DOES_NOT_FIT_AREA, logLevel = LogLevelConstants.WARN)
+    })
+    public void infiniteLoopKeepTogetherTest() throws IOException, InterruptedException {
+        String fileName = "infiniteLoopKeepTogether.pdf";
+        float fontSize = 8;
+
+        try (PdfDocument pdfDoc = new PdfDocument(new PdfWriter(destinationFolder + fileName));
+                Document doc = new Document(pdfDoc)) {
+            doc.setMargins(138, 20, 75, 20);
+
+            Table table = new Table(5);
+            table.setKeepTogether(true);
+
+            for (int i = 0; i < 37; i++) {
+                table.addCell(new Cell(1, 5).add(new Paragraph(new Text("Cell"))).setFontSize(fontSize));
+                table.startNewRow();
+            }
+
+            Table commentsTable = new Table(1);
+            Cell commentsCell = new Cell().add(new Paragraph(new Text("First line\nSecond line")));
+            commentsTable.addCell(commentsCell);
+
+            Cell outerCommentsCell = new Cell(1, 5).setFontSize(fontSize);
+            outerCommentsCell.add(commentsTable);
+            table.addCell(outerCommentsCell);
+
+            doc.add(table);
+        }
+
+        Assert.assertNull(new CompareTool().compareByContent(destinationFolder + fileName,
+                sourceFolder + "cmp_" + fileName, destinationFolder));
+    }
+
     private static class RotatedDocumentRenderer extends DocumentRenderer {
         private final PdfDocument pdfDoc;