Prevent null from being passed as occupied area in case of FULL

In case result is updated to be FULL, result's occupied area could be null:
one should check the splitRenderer's occupied area instead.

DEVSIX-5237

Autoported commit.
Original commit hash: [79e8eb90e]

Author: ars18wrw

itext.tests/itext.layout.tests/itext/layout/renderer/FlexContainerRendererTest.cs

@@ -20,8 +20,10 @@ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 You should have received a copy of the GNU Affero General Public License
 along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
+using iText.Kernel.Geom;
 using iText.Layout.Borders;
 using iText.Layout.Element;
+using iText.Layout.Layout;
 using iText.Layout.Properties;
 using iText.Test;
 
@@ -152,6 +154,15 @@ public virtual void WidthSetToChildManyChildrenFlexRendererWithMinWidthTest() {
             NUnit.Framework.Assert.AreEqual(125F, flexRenderer.GetMinMaxWidth().GetMaxWidth(), EPS);
         }
 
+        [NUnit.Framework.Test]
+        public virtual void DecreaseLayoutBoxAfterChildPlacementResultsOccupiedAreaNull() {
+            FlexContainerRenderer splitRenderer = new FlexContainerRenderer(new Div());
+            splitRenderer.occupiedArea = new LayoutArea(0, new Rectangle(0, 0));
+            LayoutResult nothing = new LayoutResult(LayoutResult.NOTHING, null, splitRenderer, null);
+            NUnit.Framework.Assert.IsNotNull(new FlexContainerRenderer(new Div()).GetOccupiedAreaInCaseNothingWasWrappedWithFull
+                (nothing, splitRenderer));
+        }
+
         [NUnit.Framework.Test]
         public virtual void WidthSetToChildManyChildrenFlexRendererWithMinWidthBiggerThanMaxWidthTest() {
             FlexContainerRenderer flexRenderer = new FlexContainerRenderer(new Div());

itext/itext.layout/itext/layout/renderer/FlexContainerRenderer.cs

@@ -198,7 +198,8 @@ internal override LayoutResult ProcessNotFullChildResult(LayoutContext layoutCon
                 if (splitRenderer != null) {
                     splitRenderer.SetChildRenderers(GetChildRenderers());
                 }
-                return new LayoutResult(LayoutResult.FULL, result.GetOccupiedArea(), splitRenderer, null, null);
+                return new LayoutResult(LayoutResult.FULL, GetOccupiedAreaInCaseNothingWasWrappedWithFull(result, splitRenderer
+                    ), splitRenderer, null, null);
             }
             else {
                 ApplyPaddings(occupiedArea.GetBBox(), paddings, true);
@@ -215,6 +216,12 @@ internal override LayoutResult ProcessNotFullChildResult(LayoutContext layoutCon
             }
         }
 
+        // TODO DEVSIX-5238 Consider this fix (perhaps it should be improved or unified) while working on the ticket
+        internal virtual LayoutArea GetOccupiedAreaInCaseNothingWasWrappedWithFull(LayoutResult result, IRenderer 
+            splitRenderer) {
+            return null != result.GetOccupiedArea() ? result.GetOccupiedArea() : splitRenderer.GetOccupiedArea();
+        }
+
         internal override bool StopLayoutingChildrenIfChildResultNotFull(LayoutResult returnResult) {
             return returnResult.GetStatus() != LayoutResult.FULL;
         }

port-hash

@@ -1 +1 @@
-9fadebfb114a7ee9ef9058a8b0c9deec71262210
+79e8eb90e75984beab3aa95b2aebeb8bd30e54da