Enable checkstyle rule for static variable names.

Enable the checkstyle rule that checks the names of
static variables and fix any violations that
are detected.

Change-Id: I2918a85b13b343285da99223829187a87ad280c3
diff --git a/conf/checkstyle/sun_checks.xml b/conf/checkstyle/sun_checks.xml
index 2e85f0e..81409fc 100644
--- a/conf/checkstyle/sun_checks.xml
+++ b/conf/checkstyle/sun_checks.xml
@@ -132,10 +132,7 @@
           <property name="severity" value="warning"/>
         </module>
 
-        <module name="StaticVariableName">
-          <property name="severity" value="warning"/>
-        </module>
-
+        <module name="StaticVariableName"/>
         <module name="TypeName"/>
 
         <!-- Checks for imports                              -->
diff --git a/src/main/java/net/onrc/onos/core/devicemanager/OnosDevice.java b/src/main/java/net/onrc/onos/core/devicemanager/OnosDevice.java
index f5a405d..157d52f 100644
--- a/src/main/java/net/onrc/onos/core/devicemanager/OnosDevice.java
+++ b/src/main/java/net/onrc/onos/core/devicemanager/OnosDevice.java
@@ -38,7 +38,7 @@
  */
 public class OnosDevice implements Serializable { //implements Comparable<OnosDevice> {
 
-    private static int ACTIVITY_TIMEOUT = 30000;
+    private static final int ACTIVITY_TIMEOUT = 30000;
 
     /**
      * The MAC address associated with this entity.
diff --git a/src/main/java/net/onrc/onos/core/packet/Ethernet.java b/src/main/java/net/onrc/onos/core/packet/Ethernet.java
index ef088db..089a481 100644
--- a/src/main/java/net/onrc/onos/core/packet/Ethernet.java
+++ b/src/main/java/net/onrc/onos/core/packet/Ethernet.java
@@ -30,7 +30,7 @@
  * @author David Erickson (daviderickson@cs.stanford.edu)
  */
 public class Ethernet extends BasePacket {
-    private static String HEXES = "0123456789ABCDEF";
+    private static final String HEXES = "0123456789ABCDEF";
     public static final short TYPE_ARP = 0x0806;
     public static final short TYPE_RARP = (short) 0x8035;
     public static final short TYPE_IPV4 = 0x0800;