[followup] Let screen reader voice a composite icon

platform/util/src/com/intellij/ui/CompositeIcon.java

@@ -8,7 +8,7 @@ import javax.swing.*;
 /**
  * An icon composing and painting a number of icons.
  */
-public interface CompositeIcon {
+public interface CompositeIcon extends Icon {
   /**
    * Returns the icon count.
    */

platform/util/src/com/intellij/ui/RetrievableIcon.java

@@ -22,10 +22,12 @@ import javax.swing.*;
 
 
 /**
- * This class is mostly for testing purposes: in case an icon is hidden behind a private or a restricted interface,
- * marking it as RetrievableIcon will help get the actual icon and perform checks.
+ * An icon wrapping and painting another icon.
  */
 public interface RetrievableIcon extends Icon {
+  /**
+   * Returns the wrapped icon.
+   */
   @Nullable
   Icon retrieveIcon();
 }