[453173] Reduce consumed memory by DBStore

Add a "!=null" check on store properties in case DBStore is created with
null properties, for example when calling CDODBUtil.createStore().

Change-Id: Iefa9f756e40b6f8a52e6058bff2ee8793c4f51b7
Task-Url: https://bugs.eclipse.org/bugs/show_bug.cgi?id=453173
Signed-off-by: Esteban Dugueperoux <esteban.dugueperoux@obeo.fr>