Make WrapperService#create not throw exceptions

Instead, let's just return null, since null can only mean one thing:
no suitable wrapper was found.

This commit also makes the appropriate changes downstream to adjust
for the update in behavior.

Author: ctrueden

src/main/java/org/scijava/plugin/AbstractWrapperService.java

@@ -52,11 +52,7 @@ public abstract class AbstractWrapperService<DT, PT extends WrapperPlugin<DT>>
 	@Override
 	public <D extends DT> PT create(final D data) {
 		final PT instance = findWrapper(data);
-		if (instance == null) {
-			throw new IllegalArgumentException("No compatible " +
-				getPluginType().getSimpleName() + " for data object: " + data);
-		}
-		instance.set(data);
+		if (instance != null) instance.set(data);
 		return instance;
 	}
 

src/main/java/org/scijava/plugin/WrapperService.java

@@ -59,8 +59,8 @@ public interface WrapperService<DT, PT extends WrapperPlugin<DT>> extends
 	/**
 	 * Creates a new plugin instance wrapping the given associated data object.
 	 * 
-	 * @throws IllegalArgumentException if the data is not compatible with any
-	 *           available plugin.
+	 * @return An appropriate plugin instance, or null if the data is not
+	 *         compatible with any available plugin.
 	 */
 	<D extends DT> PT create(D data);
 

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

@@ -36,6 +36,7 @@
 
 import org.scijava.AbstractContextual;
 import org.scijava.convert.ConvertService;
+import org.scijava.log.LogService;
 import org.scijava.module.Module;
 import org.scijava.module.ModuleCanceledException;
 import org.scijava.module.ModuleException;
@@ -58,6 +59,9 @@ public abstract class AbstractInputHarvester<P, W> extends AbstractContextual
 	implements InputHarvester<P, W>
 {
 
+	@Parameter
+	private LogService log;
+
 	@Parameter
 	private WidgetService widgetService;
 
@@ -130,6 +134,9 @@ private <T> WidgetModel addInput(final InputPanel<P, W> inputPanel,
 
 		final Class<W> widgetType = inputPanel.getWidgetComponentType();
 		final InputWidget<?, ?> widget = widgetService.create(model);
+		if (widget == null) {
+			log.warn("No widget found for input: " + model.getItem().getName());
+		}
 		if (widget != null && widget.getComponentType() == widgetType) {
 			@SuppressWarnings("unchecked")
 			final InputWidget<?, W> typedWidget = (InputWidget<?, W>) widget;

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

@@ -39,7 +39,6 @@
 import org.scijava.plugin.AbstractWrapperService;
 import org.scijava.plugin.Parameter;
 import org.scijava.plugin.Plugin;
-import org.scijava.plugin.PluginInfo;
 import org.scijava.service.Service;
 
 /**
@@ -66,22 +65,6 @@ public WidgetModel createModel(InputPanel<?, ?> inputPanel, Module module,
 			objectPool);
 	}
 
-	// -- WrapperService methods --
-
-	@Override
-	public InputWidget<?, ?> create(final WidgetModel model) {
-		for (final PluginInfo<InputWidget<?, ?>> info : getPlugins()) {
-			final InputWidget<?, ?> widget = getPluginService().createInstance(info);
-			if (widget == null) continue;
-			if (widget.supports(model)) {
-				widget.set(model);
-				return widget;
-			}
-		}
-		log.warn("No widget found for input: " + model.getItem().getName());
-		return null;
-	}
-
 	// -- PTService methods --
 
 	@Override

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

@@ -51,10 +51,6 @@ public interface WidgetService extends
 
 	// -- WrapperService methods --
 
-	/** Creates a widget that represents the given widget model. */
-	@Override
-	InputWidget<?, ?> create(WidgetModel model);
-
 	/**
 	 * Create a {@link WidgetModel} for the given module input.
 	 *