Enforce SpotBugs

Add a few missing SpotBugs annotations
Add serialVersionUID to LeastLoadBalancer$ExecutorChunkComparator since
it is Serializable.

Tested locally with:

  mvn clean -DskipTests verify

pom.xml

@@ -38,6 +38,11 @@
 	  <tag>HEAD</tag>
   </scm>
 
+	<properties>
+		<spotbugs.effort>Max</spotbugs.effort>
+		<spotbugs.threshold>Low</spotbugs.threshold>
+	</properties>
+
 	<repositories>
 		<repository>
 			<id>repo.jenkins-ci.org</id>

src/main/java/org/bstick12/jenkinsci/plugins/leastload/LeastLoadBalancer.java

@@ -24,6 +24,8 @@
 package org.bstick12.jenkinsci.plugins.leastload;
 
 import com.google.common.base.Preconditions;
+import edu.umd.cs.findbugs.annotations.CheckForNull;
+import edu.umd.cs.findbugs.annotations.NonNull;
 import hudson.init.Initializer;
 import hudson.model.Computer;
 import hudson.model.Executor;
@@ -58,7 +60,7 @@
  */
 public class LeastLoadBalancer extends LoadBalancer {
 
-    private static final Logger LOGGER = Logger.getLogger(LeastLoadBalancer.class.getCanonicalName());
+    private static final Logger LOGGER = Logger.getLogger(LeastLoadBalancer.class.getName());
 
     private static final Comparator<ExecutorChunk> EXECUTOR_CHUNK_COMPARATOR = Collections.reverseOrder(new ExecutorChunkComparator());
 
@@ -82,7 +84,8 @@ public static void register() {
     }
 
     @Override
-    public Mapping map(Task task, MappingWorksheet ws) {
+    @CheckForNull
+    public Mapping map(@NonNull Task task, MappingWorksheet ws) {
 
         try {
 
@@ -180,6 +183,7 @@ public LoadBalancer getFallBackLoadBalancer() {
     }
 
     protected static class ExecutorChunkComparator implements Comparator<ExecutorChunk>, Serializable {
+        private static final long serialVersionUID = 1L;
 
         public int compare(ExecutorChunk ec1, ExecutorChunk ec2) {
 
@@ -207,5 +211,4 @@ private boolean isIdle(Computer computer) {
         }
 
     }
-
 }