Make private static classes final

Author: garydgregory

src/test/java/org/apache/commons/csv/CSVBenchmark.java

@@ -202,7 +202,7 @@ public int parseSkifeCSV(final Blackhole bh) throws Exception {
         return callback.count;
     }
 
-    private static class CountingReaderCallback implements org.skife.csv.ReaderCallback {
+    private static final class CountingReaderCallback implements org.skife.csv.ReaderCallback {
         public int count;
 
         @Override

src/test/java/org/apache/commons/csv/PerformanceTest.java

@@ -48,7 +48,7 @@ private interface CSVParserFactory {
     }
 
     // Container for basic statistics
-    private static class Stats {
+    private static final class Stats {
         final int count;
         final int fields;
         Stats(final int c, final int f) {