diff --git a/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/CpdCommand.java b/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/CpdCommand.java
index 90d5dfc2b1..6c1a8acc7a 100644
--- a/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/CpdCommand.java
+++ b/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/CpdCommand.java
@@ -155,7 +155,7 @@ public class CpdCommand extends AbstractAnalysisPmdSubcommand {
     /**
      * Provider of candidates for valid report formats.
      */
-    private static class CpdSupportedReportFormatsCandidates implements Iterable<String> {
+    private final static class CpdSupportedReportFormatsCandidates implements Iterable<String> {
 
         @Override
         public Iterator<String> iterator() {
diff --git a/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/PmdCommand.java b/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/PmdCommand.java
index 7cf8a36dd0..94d6d3507b 100644
--- a/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/PmdCommand.java
+++ b/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/PmdCommand.java
@@ -53,7 +53,7 @@ public class PmdCommand extends AbstractAnalysisPmdSubcommand {
         for (final String rendererName : RendererFactory.supportedRenderers()) {
             final Renderer renderer = RendererFactory.createRenderer(rendererName, emptyProps);
             
-            if (renderer.getPropertyDescriptors().size() > 0) {
+            if (!renderer.getPropertyDescriptors().isEmpty()) {
                 reportPropertiesHelp.append(rendererName + ":" + System.getProperty("line.separator"));
                 for (final PropertyDescriptor<?> property : renderer.getPropertyDescriptors()) {
                     reportPropertiesHelp.append("  ").append(property.name()).append(" - ")
@@ -374,7 +374,7 @@ public class PmdCommand extends AbstractAnalysisPmdSubcommand {
     /**
      * Provider of candidates for valid report formats.
      */
-    private static class PmdSupportedReportFormatsCandidates implements Iterable<String> {
+    private final static class PmdSupportedReportFormatsCandidates implements Iterable<String> {
 
         @Override
         public Iterator<String> iterator() {
@@ -387,7 +387,7 @@ public class PmdCommand extends AbstractAnalysisPmdSubcommand {
      * 
      * Check the help for which ones are supported by each report format and possible values.
      */
-    private static class PmdReportPropertiesCandidates implements Iterable<String> {
+    private final static class PmdReportPropertiesCandidates implements Iterable<String> {
 
         @Override
         public Iterator<String> iterator() {
diff --git a/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/TreeExportCommand.java b/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/TreeExportCommand.java
index c61b6ef35b..f3aa2705ad 100644
--- a/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/TreeExportCommand.java
+++ b/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/TreeExportCommand.java
@@ -40,7 +40,7 @@ public class TreeExportCommand extends AbstractPmdSubcommand {
         
         for (final TreeRendererDescriptor renderer : TreeRenderers.registeredRenderers()) {
             final PropertySource propertyBundle = renderer.newPropertyBundle();
-            if (propertyBundle.getPropertyDescriptors().size() > 0) {
+            if (!propertyBundle.getPropertyDescriptors().isEmpty()) {
                 reportPropertiesHelp.append(renderer.id() + ":" + System.getProperty("line.separator"));
                 for (final PropertyDescriptor<?> property : propertyBundle.getPropertyDescriptors()) {
                     reportPropertiesHelp.append("  ").append(property.name()).append(" - ")
@@ -121,7 +121,7 @@ public class TreeExportCommand extends AbstractPmdSubcommand {
     /**
      * Provides completion candidates for the report format.
      */
-    private static class TreeRenderersCandidates implements Iterable<String> {
+    private final static class TreeRenderersCandidates implements Iterable<String> {
 
         @Override
         public Iterator<String> iterator() {
@@ -134,7 +134,7 @@ public class TreeExportCommand extends AbstractPmdSubcommand {
      * 
      * Check the help for which ones are supported by each report format and possible values.
      */
-    private static class TreeExportReportPropertiesCandidates implements Iterable<String> {
+    private final static class TreeExportReportPropertiesCandidates implements Iterable<String> {
 
         @Override
         public Iterator<String> iterator() {