Cosmetic fix about constant name

Change-Id: I995c9275cf5be04af5f268e22dcc96e0a6aeb5b7
diff --git a/providers/snmp/device/src/test/java/org/onosproject/provider/snmp/device/impl/SnmpDeviceProviderTest.java b/providers/snmp/device/src/test/java/org/onosproject/provider/snmp/device/impl/SnmpDeviceProviderTest.java
index 462e05e..16e56e0 100644
--- a/providers/snmp/device/src/test/java/org/onosproject/provider/snmp/device/impl/SnmpDeviceProviderTest.java
+++ b/providers/snmp/device/src/test/java/org/onosproject/provider/snmp/device/impl/SnmpDeviceProviderTest.java
@@ -98,7 +98,7 @@
     private final InputStream jsonStream = SnmpDeviceProviderTest.class
             .getResourceAsStream("/device.json");
     private final ObjectMapper mapper = new ObjectMapper();
-    private final String KEY = "snmp";
+    private static final String KEY = "snmp";
 
 
     @Before