Fixed some minor build warnings/findbugs

pom.xml

@@ -4,7 +4,7 @@
     <parent>
         <groupId>org.jenkins-ci.plugins</groupId>
         <artifactId>plugin</artifactId>
-        <version>2.6</version>
+        <version>2.20</version>
     </parent>
 
     <artifactId>msbuild</artifactId>

src/main/java/hudson/plugins/msbuild/MSBuildErrorNote.java

@@ -28,6 +28,7 @@ public ConsoleAnnotator annotate(Object context, MarkupText text, int charPos) {
     @Extension @Symbol("msbuildError")
     public static final class DescriptorImpl extends ConsoleAnnotationDescriptor {
 
+        @Override
         public String getDisplayName() {
             return Messages.MsBuildBuilder_ErrorNoteDescription();
         }

src/main/java/hudson/plugins/msbuild/MSBuildWarningNote.java

@@ -28,6 +28,7 @@ public ConsoleAnnotator annotate(Object context, MarkupText text, int charPos) {
     @Extension @Symbol("msbuildWarning")
     public static final class DescriptorImpl extends ConsoleAnnotationDescriptor {
 
+        @Override
         public String getDisplayName() {
             return Messages.MsBuildBuilder_WarningNoteDescription();
         }

src/main/java/hudson/plugins/msbuild/MsBuildBuilder.java

@@ -161,7 +161,7 @@ public boolean perform(AbstractBuild<?, ?> build, Launcher launcher, BuildListen
 
         //Build /P:key1=value1;key2=value2 ...
         Map<String, String> propertiesVariables = getPropertiesVariables(build);
-        if (buildVariablesAsProperties && propertiesVariables.size() != 0) {
+        if (buildVariablesAsProperties && !propertiesVariables.isEmpty()) {
             StringBuffer parameters = new StringBuffer();
             parameters.append("/p:");
             for (Map.Entry<String, String> entry : propertiesVariables.entrySet()) {
@@ -178,7 +178,7 @@ public boolean perform(AbstractBuild<?, ?> build, Launcher launcher, BuildListen
             normalizedFile = msBuildFile.replaceAll("[\t\r\n]+", " ");
             normalizedFile = Util.replaceMacro(normalizedFile, env);
             normalizedFile = Util.replaceMacro(normalizedFile, build.getBuildVariables());
-            if (normalizedFile.length() > 0) {
+            if (!normalizedFile.isEmpty()) {
                 args.add(normalizedFile);
             }
         }
@@ -223,7 +223,7 @@ private Map<String, String> getPropertiesVariables(AbstractBuild build) {
         Map<String, String> buildVariables = build.getBuildVariables();
 
         final Set<String> sensitiveBuildVariables = build.getSensitiveBuildVariables();
-        if (sensitiveBuildVariables == null || sensitiveBuildVariables.size() == 0) {
+        if (sensitiveBuildVariables == null || sensitiveBuildVariables.isEmpty()) {
             return buildVariables;
         }
 
@@ -258,7 +258,7 @@ static String getToolFullPath(Launcher launcher, String pathToTool, String execN
 
     @Override
     public Descriptor<Builder> getDescriptor() {
-        return (DescriptorImpl) super.getDescriptor();
+        return super.getDescriptor();
     }
 
     /**
@@ -292,6 +292,7 @@ public DescriptorImpl() {
             load();
         }
 
+        @Override
         public String getDisplayName() {
             return Messages.MsBuildBuilder_DisplayName();
         }

src/main/java/hudson/plugins/msbuild/MsBuildInstallation.java

@@ -43,18 +43,20 @@
  */
 public final class MsBuildInstallation extends ToolInstallation implements NodeSpecific<MsBuildInstallation>, EnvironmentSpecific<MsBuildInstallation> {
 
-    private String defaultArgs;
+    private final String defaultArgs;
 
     @DataBoundConstructor
     public MsBuildInstallation(String name, String home, String defaultArgs) {
         super(name, home, null);
         this.defaultArgs = Util.fixEmpty(defaultArgs);
     }
 
+    @Override
     public MsBuildInstallation forNode(Node node, TaskListener log) throws IOException, InterruptedException {
         return new MsBuildInstallation(getName(), translateFor(node, log), getDefaultArgs());
     }
 
+    @Override
     public MsBuildInstallation forEnvironment(EnvVars environment) {
         return new MsBuildInstallation(getName(), environment.expand(getHome()), getDefaultArgs());
     }
@@ -66,6 +68,7 @@ public String getDefaultArgs() {
     @Extension @Symbol("msbuild")
     public static class DescriptorImpl extends ToolDescriptor<MsBuildInstallation> {
 
+        @Override
         public String getDisplayName() {
             return "MSBuild";
         }

src/test/java/hudson/plugins/msbuild/MsBuildKillingVetoTest.java

@@ -78,6 +78,7 @@ public void testLeavesOthersAlone() {
 
     private IOSProcess mockProcess(final String... cmdLine) {
         return new IOSProcess() {
+            @Override
             public void killRecursively() throws InterruptedException {
             }