Index: trunk/test/performance/org/openstreetmap/josm/PerformanceTestUtils.java
===================================================================
--- trunk/test/performance/org/openstreetmap/josm/PerformanceTestUtils.java	(revision 8623)
+++ trunk/test/performance/org/openstreetmap/josm/PerformanceTestUtils.java	(revision 8632)
@@ -6,8 +6,8 @@
  * @author Michael Zangl
  */
-public class PerformanceTestUtils {
+public final class PerformanceTestUtils {
     /**
      * A timer that measures the time from it's creation to the {@link #done()} call.
-    * @author Michael Zangl
+     * @author Michael Zangl
      */
     public static class PerformanceTestTimer {
Index: trunk/test/performance/org/openstreetmap/josm/data/osm/KeyValuePerformanceTest.java
===================================================================
--- trunk/test/performance/org/openstreetmap/josm/data/osm/KeyValuePerformanceTest.java	(revision 8623)
+++ trunk/test/performance/org/openstreetmap/josm/data/osm/KeyValuePerformanceTest.java	(revision 8632)
@@ -26,5 +26,5 @@
     private static final int TEST_STRING_COUNT = 10000;
     private static final int STRING_INTERN_TESTS = 5000000;
-    private static final double[] TAG_NODE_RATIOS = new double[] { .05, .3, 3, 20, 200 };
+    private static final double[] TAG_NODE_RATIOS = new double[] {.05, .3, 3, 20, 200};
     private ArrayList<String> testStrings = new ArrayList<>();
     private Random random;
Index: trunk/test/performance/org/openstreetmap/josm/data/osm/OsmDataGenerator.java
===================================================================
--- trunk/test/performance/org/openstreetmap/josm/data/osm/OsmDataGenerator.java	(revision 8623)
+++ trunk/test/performance/org/openstreetmap/josm/data/osm/OsmDataGenerator.java	(revision 8632)
@@ -14,14 +14,18 @@
  * @author Michael Zangl
  */
-public class OsmDataGenerator {
+public final class OsmDataGenerator {
     private static final int DEFAULT_KEY_VALUE_RATIO = 3;
     private static final int DEFAULT_NODE_COUNT = 1000;
     private static final String DATA_DIR = "data_nodist" + File.separator + "osmfiles";
 
+    private OsmDataGenerator() {
+        // private constructor for utility classes
+    }
+
     /**
      * A generator that generates test data by filling a data set.
      * @author Michael Zangl
      */
-    public static abstract class DataGenerator {
+    public abstract static class DataGenerator {
         private String datasetName;
         protected final Random random;
@@ -57,5 +61,5 @@
         /**
          * Create a random node and add it to the dataset.
-         * @return
+         * @return a random node
          */
         protected Node createRandomNode(DataSet ds) {
@@ -94,5 +98,5 @@
     /**
      * A data generator that generates a bunch of random nodes.
-    * @author Michael Zangl
+     * @author Michael Zangl
      */
     public static class NodeDataGenerator extends DataGenerator {
@@ -100,5 +104,5 @@
         private final int nodeCount;
 
-        private NodeDataGenerator(String datasetName, int nodeCount) {
+        protected NodeDataGenerator(String datasetName, int nodeCount) {
             super(datasetName);
             this.nodeCount = nodeCount;
@@ -124,7 +128,7 @@
     /**
      * A data generator that generates a bunch of random nodes and fills them with keys/values.
-    * @author Michael Zangl
-     */
-    public static class KeyValueDataGenerator extends NodeDataGenerator {
+     * @author Michael Zangl
+     */
+    public static final class KeyValueDataGenerator extends NodeDataGenerator {
 
         private static final int VALUE_COUNT = 200;