Fix writing issues (#7749)

* A root component with @DesignRoot must always use its superclass for
default values. Otherwise the written design will be empty as the
design is read in the constructor.

* A component which is not the root must not write its component tree
if the component tree is generated in the constructor. This is a
simplification which should be good enough for most cases (can't add
children in constructor and also using addComponent - in this case
the component added with addComponent will not be written).

* Test cases for nested templates

Change-Id: I3a384d1d8654b9865a3a790ebeb055a300a62135

1 files changed, 2 insertions, 2 deletions

diff --git a/server/src/com/vaadin/ui/AbstractSplitPanel.java b/server/src/com/vaadin/ui/AbstractSplitPanel.java
index 9c33665c1c..4c85311075 100644
--- a/server/src/com/vaadin/ui/AbstractSplitPanel.java
+++ b/server/src/com/vaadin/ui/AbstractSplitPanel.java
@@ -627,8 +627,8 @@ public abstract class AbstractSplitPanel extends AbstractComponentContainer {
         super.writeDesign(design, designContext);
         // handle custom attributes (write only if a value is not the
         // default value)
-        AbstractSplitPanel def = designContext.getDefaultInstance(this
-                .getClass());
+        AbstractSplitPanel def = (AbstractSplitPanel) designContext
+                .getDefaultInstance(this);
         if (getSplitPosition() != def.getSplitPosition()
                 || !def.getSplitPositionUnit().equals(getSplitPositionUnit())) {
             String splitPositionString = asString(getSplitPosition())