Improve comments

Author: sungshik

src/main/java/engineering/swat/watch/WatchEvent.java

@@ -135,7 +135,7 @@ public String toString() {
      * <p>
      * Note: This method applies different logic to compare events than (the
      * default implementation of) method {@link #equals(Object)}, which
-     * shouldn't be overridden. This is because events should norminally be
+     * shouldn't be overridden. This is because events should normally be
      * compared in terms of their identities (e.g., two successive modifications
      * of the same file result in events that are equivalent, but not equal;
      * they need to be distinguishable in collections).

src/test/java/engineering/swat/watch/TestHelper.java

@@ -79,6 +79,10 @@ public static <T> Stream<T> streamOf(T[] values, int repetitions, boolean sortBy
         }
     }
 
+    /**
+     * Helper class to keep track of a list of events and query it (on a
+     * slightly higher level of abstraction than manipulation of event streams).
+     */
     public static class Bookkeeper implements Consumer<WatchEvent> {
         private final Queue<WatchEvent> events = new ConcurrentLinkedQueue<>();