Sonar fixes

Rule: Use isEmpty() to check whether the collection is empty or not.

Change-Id: Ib5ab56b2263623b297db56c5cac2c2ee80e12725
diff --git a/providers/bgp/cli/src/main/java/org/onosproject/bgp/cli/BgpConfiguration.java b/providers/bgp/cli/src/main/java/org/onosproject/bgp/cli/BgpConfiguration.java
index d34c80e..f567e8d 100644
--- a/providers/bgp/cli/src/main/java/org/onosproject/bgp/cli/BgpConfiguration.java
+++ b/providers/bgp/cli/src/main/java/org/onosproject/bgp/cli/BgpConfiguration.java
@@ -87,7 +87,7 @@
             TreeMap<String, BgpPeerCfg> displayPeerTree = bgpCfg.getPeerTree();
             Set<String> peerKey = displayPeerTree.keySet();
             if (peer != null) {
-                if (peerKey.size() > 0) {
+                if (!peerKey.isEmpty()) {
                     for (String peerIdKey : peerKey) {
                         bgpPeerCfg = displayPeerTree.get(peerIdKey);
                         bgpConnectPeer = bgpPeerCfg.connectPeer();
@@ -101,7 +101,7 @@
                     }
                 }
             } else {
-                if (peerKey.size() > 0) {
+                if (!peerKey.isEmpty()) {
                     for (String peerIdKey : peerKey) {
                         bgpPeerCfg = displayPeerTree.get(peerIdKey);
                         bgpConnectPeer = bgpPeerCfg.connectPeer();
diff --git a/providers/bgp/cli/src/main/java/org/onosproject/bgp/cli/BgpExceptions.java b/providers/bgp/cli/src/main/java/org/onosproject/bgp/cli/BgpExceptions.java
index 2f129ba..4a70556 100644
--- a/providers/bgp/cli/src/main/java/org/onosproject/bgp/cli/BgpExceptions.java
+++ b/providers/bgp/cli/src/main/java/org/onosproject/bgp/cli/BgpExceptions.java
@@ -64,7 +64,7 @@
             this.bgpController = get(BgpController.class);
             Map<String, List<String>> activeSessionExceptionMap = bgpController.activeSessionMap();
             activeSessionExceptionkeySet = activeSessionExceptionMap.keySet();
-            if (activeSessionExceptionkeySet.size() > 0) {
+            if (!activeSessionExceptionkeySet.isEmpty()) {
                 if (peerId != null) {
                     if (activeSessionExceptionkeySet.contains(peerId)) {
                         for (String peerIdKey : activeSessionExceptionkeySet) {
@@ -76,7 +76,7 @@
                     }
                 } else {
                     activeSessionExceptionkeySet = activeSessionExceptionMap.keySet();
-                    if (activeSessionExceptionkeySet.size() > 0) {
+                    if (!activeSessionExceptionkeySet.isEmpty()) {
                         for (String peerId : activeSessionExceptionkeySet) {
                             print("PeerId = %s, Exception = %s ", peerId, activeSessionExceptionMap.get(peerId));
                         }
@@ -93,7 +93,7 @@
             this.bgpController = get(BgpController.class);
             Map<String, List<String>> closedSessionExceptionMap = bgpController.closedSessionMap();
             closedSessionExceptionKeySet = closedSessionExceptionMap.keySet();
-            if (closedSessionExceptionKeySet.size() > 0) {
+            if (!closedSessionExceptionKeySet.isEmpty()) {
                 if (peerId != null) {
                     if (closedSessionExceptionKeySet.contains(peerId)) {
                         for (String peerIdKey : closedSessionExceptionKeySet) {
@@ -105,7 +105,7 @@
                     }
                 } else {
                     closedSessionExceptionKeySet = closedSessionExceptionMap.keySet();
-                    if (closedSessionExceptionKeySet.size() > 0) {
+                    if (!closedSessionExceptionKeySet.isEmpty()) {
                         for (String peerId : closedSessionExceptionKeySet) {
                             print("PeerId = %s, Exception = %s", peerId, closedSessionExceptionMap.get(peerId));
                         }
diff --git a/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java b/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java
index c1e2843..9c3ca0f 100644
--- a/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java
+++ b/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java
@@ -713,7 +713,7 @@
          */
         private PortDescription buildPortDescription(PortDescPropertyType ptype, OFPortOptical port,
                 OpenFlowOpticalSwitch opsw) {
-            checkArgument(port.getDesc().size() >= 1);
+            checkArgument(!port.getDesc().isEmpty());
 
             // Minimally functional fixture. This needs to be fixed as we add better support.
             PortNumber portNo = PortNumber.portNumber(port.getPortNo().getPortNumber());
@@ -790,7 +790,7 @@
             // Use the alias name if it's available
             String name = port.getName();
             List<OFCalientPortDescProp> props = port.getProperties();
-            if (props != null && props.size() > 0) {
+            if (props != null && !props.isEmpty()) {
                 OFCalientPortDescPropOptical propOptical = (OFCalientPortDescPropOptical) props.get(0);
                 if (propOptical != null) {
                     name = propOptical.getInAlias();
diff --git a/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowModBuilderVer13.java b/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowModBuilderVer13.java
index 44b839b..e63fa69 100644
--- a/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowModBuilderVer13.java
+++ b/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowModBuilderVer13.java
@@ -131,10 +131,10 @@
         if (treatment.clearedDeferred()) {
             instructions.add(factory().instructions().clearActions());
         }
-        if (immediateActions.size() > 0) {
+        if (!immediateActions.isEmpty()) {
             instructions.add(factory().instructions().applyActions(immediateActions));
         }
-        if (deferredActions.size() > 0) {
+        if (!deferredActions.isEmpty()) {
             instructions.add(factory().instructions().writeActions(deferredActions));
         }
         if (treatment.tableTransition() != null) {
@@ -172,13 +172,13 @@
         List<OFInstruction> instructions = Lists.newLinkedList();
 
 
-        if (immediateActions.size() > 0) {
+        if (!immediateActions.isEmpty()) {
             instructions.add(factory().instructions().applyActions(immediateActions));
         }
         if (treatment.clearedDeferred()) {
             instructions.add(factory().instructions().clearActions());
         }
-        if (deferredActions.size() > 0) {
+        if (!deferredActions.isEmpty()) {
             instructions.add(factory().instructions().writeActions(deferredActions));
         }
         if (treatment.tableTransition() != null) {
diff --git a/providers/openflow/group/src/main/java/org/onosproject/provider/of/group/impl/GroupBucketEntryBuilder.java b/providers/openflow/group/src/main/java/org/onosproject/provider/of/group/impl/GroupBucketEntryBuilder.java
index 1ba438d..58cf18e 100644
--- a/providers/openflow/group/src/main/java/org/onosproject/provider/of/group/impl/GroupBucketEntryBuilder.java
+++ b/providers/openflow/group/src/main/java/org/onosproject/provider/of/group/impl/GroupBucketEntryBuilder.java
@@ -119,7 +119,7 @@
         TrafficTreatment.Builder builder = DefaultTrafficTreatment.builder();
 
         // If this is a drop rule
-        if (actions.size() == 0) {
+        if (actions.isEmpty()) {
             builder.drop();
             return builder.build();
         }
diff --git a/providers/openflow/meter/src/main/java/org/onosproject/provider/of/meter/impl/MeterModBuilder.java b/providers/openflow/meter/src/main/java/org/onosproject/provider/of/meter/impl/MeterModBuilder.java
index 5d2a101..406337b 100644
--- a/providers/openflow/meter/src/main/java/org/onosproject/provider/of/meter/impl/MeterModBuilder.java
+++ b/providers/openflow/meter/src/main/java/org/onosproject/provider/of/meter/impl/MeterModBuilder.java
@@ -155,6 +155,6 @@
     private void validate() {
         checkNotNull(id, "id cannot be null");
         checkNotNull(bands, "Must have bands");
-        checkArgument(bands.size() > 0, "Must have at lease one band");
+        checkArgument(!bands.isEmpty(), "Must have at lease one band");
     }
 }
diff --git a/providers/pcep/cli/src/main/java/org/onosproject/pcep/cli/PcepSessionCommand.java b/providers/pcep/cli/src/main/java/org/onosproject/pcep/cli/PcepSessionCommand.java
index 420dd0c..f7407ec 100644
--- a/providers/pcep/cli/src/main/java/org/onosproject/pcep/cli/PcepSessionCommand.java
+++ b/providers/pcep/cli/src/main/java/org/onosproject/pcep/cli/PcepSessionCommand.java
@@ -93,7 +93,7 @@
             pcepSessionKeySet = pcepSessionMap.keySet();
             pcepSessionIdKeySet = pcepSessionIdMap.keySet();
             if (peer != null) {
-                if (pcepSessionKeySet.size() > 0) {
+                if (!pcepSessionKeySet.isEmpty()) {
                     if (pcepSessionKeySet.contains(peer)) {
                         for (String pcepSessionPeer : pcepSessionKeySet) {
                             if (pcepSessionPeer.equals(peer)) {
@@ -116,7 +116,7 @@
                     }
                 }
             } else {
-                if (pcepSessionKeySet.size() > 0) {
+                if (!pcepSessionKeySet.isEmpty()) {
                     for (String pcepSessionPeer : pcepSessionKeySet) {
                         for (String pcepSessionId : pcepSessionIdKeySet) {
                             if (pcepSessionId.equals(pcepSessionPeer)) {
@@ -143,7 +143,7 @@
             this.pcepClientController = get(PcepClientController.class);
             Map<String, List<String>> pcepSessionFailureReasonMap = pcepClientController.getPcepExceptions();
             pcepSessionFailurekeySet = pcepSessionFailureReasonMap.keySet();
-            if (pcepSessionFailurekeySet.size() > 0) {
+            if (!pcepSessionFailurekeySet.isEmpty()) {
                 if (peer != null) {
                     if (pcepSessionFailurekeySet.contains(peer)) {
                         for (String pcepSessionPeerId : pcepSessionFailurekeySet) {
@@ -158,7 +158,7 @@
 
                 } else {
                     pcepSessionFailurekeySet = pcepSessionFailureReasonMap.keySet();
-                    if (pcepSessionFailurekeySet.size() > 0) {
+                    if (!pcepSessionFailurekeySet.isEmpty()) {
                         for (String pcepSessionPeerId : pcepSessionFailurekeySet) {
                             pcepSessionExceptions = pcepSessionFailureReasonMap.get(pcepSessionPeerId);
                             print("PeerId = %s, FailureReason = %s", pcepSessionPeerId, pcepSessionExceptions);
@@ -181,7 +181,7 @@
             this.pcepClientController = get(PcepClientController.class);
             Map<Integer, Integer> pcepErrorMsgMap = pcepClientController.getPcepErrorMsg();
             pcepErrorMsgKey = pcepErrorMsgMap.keySet();
-            if (pcepErrorMsgKey.size() > 0) {
+            if (!pcepErrorMsgKey.isEmpty()) {
                 for (Integer errorType : pcepErrorMsgKey) {
                     pcepErrorValue = pcepErrorMsgMap.get(errorType);
                     pcepErrorType = PcepErrorType.values()[errorType];
diff --git a/providers/pcep/tunnel/src/main/java/org/onosproject/provider/pcep/tunnel/impl/PcepTunnelProvider.java b/providers/pcep/tunnel/src/main/java/org/onosproject/provider/pcep/tunnel/impl/PcepTunnelProvider.java
index 767d026..caa317d 100644
--- a/providers/pcep/tunnel/src/main/java/org/onosproject/provider/pcep/tunnel/impl/PcepTunnelProvider.java
+++ b/providers/pcep/tunnel/src/main/java/org/onosproject/provider/pcep/tunnel/impl/PcepTunnelProvider.java
@@ -720,7 +720,7 @@
     // Creates a path that leads through the given devices.
     private Path createPath(List<PcepHopNodeDescription> hopList,
                             PathType pathtype, PathState pathState) {
-        if (hopList == null || hopList.size() == 0) {
+        if (hopList == null || hopList.isEmpty()) {
             return null;
         }
         List<Link> links = new ArrayList<>();
@@ -947,7 +947,7 @@
             llSubObjects = createPcepPath(path);
         }
 
-        if (llSubObjects == null || llSubObjects.size() == 0) {
+        if (llSubObjects == null || llSubObjects.isEmpty()) {
             log.error("There is no link information to create tunnel");
             return null;
         }
@@ -1053,7 +1053,7 @@
 
             LinkedList<PcInitiatedLspRequest> llPcInitiatedLspRequestList = createPcInitiatedLspReqList(tunnel, path,
                                                                                                         pc, srpId);
-            if (llPcInitiatedLspRequestList == null || llPcInitiatedLspRequestList.size() == 0) {
+            if (llPcInitiatedLspRequestList == null || llPcInitiatedLspRequestList.isEmpty()) {
                 log.error("Failed to create PcInitiatedLspRequestList");
                 return;
             }
@@ -1735,7 +1735,7 @@
             checkNotNull(eroObj);
             List<Object> subObjList = new ArrayList<>();
             LinkedList<PcepValueType> llSubObj = eroObj.getSubObjects();
-            if (0 == llSubObj.size()) {
+            if (llSubObj.isEmpty()) {
                 log.error("ERO in report message does not have hop information");
                 return new ArrayList<>();
             }