docs: update twin

twin/src/main/java/com/iluwatar/twin/BallItem.java

@@ -29,7 +29,7 @@ import lombok.extern.slf4j.Slf4j;
 
 /**
  * This class represents a Ball which extends {@link GameItem} and implements the logic for ball
- * item, like move and draw. It hold a reference of {@link BallThread} to delegate the suspend and
+ * item, like move and draw. It holds a reference of {@link BallThread} to delegate the suspend and
  * resume task.
  */
 @Slf4j

twin/src/main/java/com/iluwatar/twin/BallThread.java

@@ -29,7 +29,7 @@ import lombok.extern.slf4j.Slf4j;
 
 /**
  * This class is a UI thread for drawing the {@link BallItem}, and provide the method for suspend
- * and resume. It hold the reference of {@link BallItem} to delegate the draw task.
+ * and resume. It holds the reference of {@link BallItem} to delegate the draw task.
  */
 
 @Slf4j

twin/src/test/java/com/iluwatar/twin/BallItemTest.java

@@ -108,7 +108,7 @@ class BallItemTest {
   /**
    * Logging Appender Implementation
    */
-  class InMemoryAppender extends AppenderBase<ILoggingEvent> {
+  static class InMemoryAppender extends AppenderBase<ILoggingEvent> {
     private final List<ILoggingEvent> log = new LinkedList<>();
 
     public InMemoryAppender() {