coverity#1326438 Dereference null return value

and

coverity#1326439 Dereference null return value

Change-Id: Idf7e6f34accfb5d5b98a62f6ad221c325e24586a

reportbuilder/java/org/libreoffice/report/pentaho/layoutprocessor/OfficeGroupLayoutController.java

@@ -109,6 +109,12 @@ public class OfficeGroupLayoutController extends SectionLayoutController
 
             final OfficeGroup group = (OfficeGroup) getElement();
             final OfficeGroupSection header = group.getHeader();
+
+            if (header == null)
+            {
+                return controller;
+            }
+
             controller.waitForJoin = true;
             return processChild(controller, header, getFlowController());
         }
@@ -127,6 +133,12 @@ public class OfficeGroupLayoutController extends SectionLayoutController
 
             final OfficeGroup group = (OfficeGroup) getElement();
             final OfficeGroupSection footer = group.getFooter();
+
+            if (footer == null)
+            {
+                return controller;
+            }
+
             controller.waitForJoin = true;
             return processChild(controller, footer, getFlowController());
         }