Make default primitive operation timeout configurable

Change-Id: I340085f5031fd6a56951cc66e7bc8f8f2f64ac37
diff --git a/core/api/src/main/java/org/onosproject/store/service/DistributedPrimitive.java b/core/api/src/main/java/org/onosproject/store/service/DistributedPrimitive.java
index 620e16d..8ce1e8b 100644
--- a/core/api/src/main/java/org/onosproject/store/service/DistributedPrimitive.java
+++ b/core/api/src/main/java/org/onosproject/store/service/DistributedPrimitive.java
@@ -133,7 +133,8 @@
     /**
      * Default timeout for primitive operations.
      */
-    long DEFAULT_OPERATION_TIMEOUT_MILLIS = 15000L;
+    long DEFAULT_OPERATION_TIMEOUT_MILLIS = Long.parseLong(
+            System.getProperty("onos.cluster.primitive.operationTimeoutMillis", String.valueOf(15000)));
 
     /**
      * Use {@link #DEFAULT_OPERATION_TIMEOUT_MILLIS} instead.