Add javadoc, pointing developers to UndoUtils and its wrap method

Author: JordanMartinez

richtextfx/src/main/java/org/fxmisc/richtext/GenericStyledArea.java

@@ -130,6 +130,14 @@
  * <p>Additionally, when overriding the default user-interaction behavior, remember to include a call
  * to {@link #requestFollowCaret()}.</p>
  *
+ * <h3>Setting the area's {@link UndoManager}</h3>
+ *
+ * <p>
+ *     The default UndoManager can undo/redo either {@link PlainTextChange}s or {@link RichTextChange}s. To create
+ *     your own specialized version that may use changes different than these (or a combination of these changes
+ *     with others), create them using the convenient factory methods in {@link UndoUtils}.
+ * </p>
+ *
  * <h3>Overriding default keyboard behavior</h3>
  *
  * {@code StyledTextArea} uses {@code KEY_TYPED} handler to handle ordinary

richtextfx/src/main/java/org/fxmisc/richtext/model/UndoActions.java

@@ -13,6 +13,11 @@ public interface UndoActions {
      * Undo manager of this text area.
      */
     UndoManager getUndoManager();
+
+    /**
+     * Closes the current area's undo manager before setting it to the given one. <b>Note:</b> to create your
+     * own {@link UndoManager}, see the convenient factory methods in {@link org.fxmisc.richtext.util.UndoUtils}.
+     */
     void setUndoManager(UndoManager undoManager);
 
     default void undo() { getUndoManager().undo(); }

richtextfx/src/main/java/org/fxmisc/richtext/util/UndoUtils.java

@@ -13,6 +13,12 @@
 
 /**
  * A class filled with factory methods to help easily construct an {@link UndoManager} for a {@link GenericStyledArea}.
+ *
+ * <p>
+ *     To create an UndoManager that will prevent incoming changes from merging with the previous one after a period
+ *     of user inactivity (via {@link UndoManager#preventMerge()}),
+ *     use {@link #wrap(UndoManager, EventStream, Duration)}.
+ * </p>
  */
 public final class UndoUtils {