Adding reference to DefaultDriverProviderService in Corsa drivers to enforce correct ordering of driver loading at ONOS startup

Change-Id: I4c46faf5682a02c667ff81ab5edff0dd539e7d1b
diff --git a/drivers/corsa/src/main/java/org/onosproject/drivers/corsa/CorsaDriversLoader.java b/drivers/corsa/src/main/java/org/onosproject/drivers/corsa/CorsaDriversLoader.java
index b2ad9ee..33eb06e 100644
--- a/drivers/corsa/src/main/java/org/onosproject/drivers/corsa/CorsaDriversLoader.java
+++ b/drivers/corsa/src/main/java/org/onosproject/drivers/corsa/CorsaDriversLoader.java
@@ -17,13 +17,23 @@
 package org.onosproject.drivers.corsa;
 
 import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
 import org.onosproject.net.driver.AbstractDriverLoader;
+import org.onosproject.net.driver.DefaultDriverProviderService;
 
 /**
  * Loader for Corsa device drivers.
  */
 @Component(immediate = true)
 public class CorsaDriversLoader extends AbstractDriverLoader {
+
+    //This reference is needed to enforce loading of the default drivers before
+    //the corsa drivers at ONOS startup if corsa.drivers is specified
+    //in the ONOS_APPS variable.
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private DefaultDriverProviderService defaultDriverProviderService;
+
     public CorsaDriversLoader() {
         super("/corsa-drivers.xml");
     }