WidgetModel: deprecate getChoices & move to iface

The getChoices() method always converts the choices to strings.
We cannot always go back from string to original object -- e.g.,
for enums which override toString() to print something nice.

Better to just use the original choices from getItem().getChoices().

This also makes the getChoices method more concise.

Author: ctrueden

src/main/java/org/scijava/widget/DefaultWidgetModel.java

@@ -219,17 +219,6 @@ public Number getStepSize() {
 		return NumberUtils.toNumber("1", item.getType());
 	}
 
-	@Override
-	public String[] getChoices() {
-		final List<?> choicesList = item.getChoices();
-		if (choicesList == null) return null;
-		final String[] choices = new String[choicesList.size()];
-		for (int i = 0; i < choices.length; i++) {
-			choices[i] = objectService.getName(choicesList.get(i));
-		}
-		return choices;
-	}
-
 	@Override
 	public String getText() {
 		final Object value = getValue();

src/main/java/org/scijava/widget/WidgetModel.java

@@ -134,13 +134,13 @@ public interface WidgetModel extends Contextual {
 	 */
 	Number getStepSize();
 
-	/**
-	 * Gets the multiple choice list for the module input.
-	 * 
-	 * @return The available choices, or an empty list if not multiple choice.
-	 * @see ChoiceWidget
-	 */
-	String[] getChoices();
+	/** @deprecated Use {@code getItem().getChoices()} instead. */
+	@Deprecated
+	default String[] getChoices() {
+		return getItem().getChoices().stream() //
+			.map(choice -> choice.toString()) //
+			.toArray(String[]::new);
+	}
 
 	/**
 	 * Gets the input's value rendered as a string.