Give module items a place to store a default value

The ModuleItem#getDefaultValue() method returns the intended default
value for the item, or null if none such.

And the MutableModuleItem#setDefaultValue(T) method lets it be set.

Of course, as of this commit, nothing respects the setting yet.

Author: ctrueden

src/main/java/org/scijava/module/AbstractModuleItem.java

@@ -74,6 +74,7 @@ public String toString() {
 		sm.append("persistKey", getPersistKey());
 		sm.append("callback", getCallback());
 		sm.append("widgetStyle", getWidgetStyle());
+		sm.append("default", getDefaultValue());
 		sm.append("min", getMinimumValue());
 		sm.append("max", getMaximumValue());
 		sm.append("softMin", getSoftMinimum());
@@ -217,6 +218,11 @@ public String getWidgetStyle() {
 		return null;
 	}
 
+	@Override
+	public T getDefaultValue() {
+		return null;
+	}
+
 	@Override
 	public T getMinimumValue() {
 		return null;

src/main/java/org/scijava/module/DefaultMutableModuleItem.java

@@ -59,6 +59,7 @@ public class DefaultMutableModuleItem<T> extends AbstractModuleItem<T>
 	private String initializer;
 	private String callback;
 	private String widgetStyle;
+	private T defaultValue;
 	private T minimumValue;
 	private T maximumValue;
 	private T softMinimum;
@@ -171,6 +172,11 @@ public void setWidgetStyle(final String widgetStyle) {
 		this.widgetStyle = widgetStyle;
 	}
 
+	@Override
+	public void setDefaultValue(final T defaultValue) {
+		this.defaultValue = defaultValue;
+	}
+
 	@Override
 	public void setMinimumValue(final T minimumValue) {
 		this.minimumValue = minimumValue;
@@ -259,6 +265,11 @@ public String getWidgetStyle() {
 		return widgetStyle;
 	}
 
+	@Override
+	public T getDefaultValue() {
+		return defaultValue;
+	}
+
 	@Override
 	public T getMinimumValue() {
 		return minimumValue;

src/main/java/org/scijava/module/ModuleItem.java

@@ -146,6 +146,9 @@ public interface ModuleItem<T> extends BasicDetails {
 	 */
 	String getWidgetStyle();
 
+	/** Gets the default value. */
+	T getDefaultValue();
+
 	/** Gets the minimum allowed value (if applicable). */
 	T getMinimumValue();
 

src/main/java/org/scijava/module/MutableModuleItem.java

@@ -60,6 +60,8 @@ public interface MutableModuleItem<T> extends ModuleItem<T> {
 
 	void setWidgetStyle(String widgetStyle);
 
+	void setDefaultValue(T defaultValue);
+
 	void setMinimumValue(T minimumValue);
 
 	void setMaximumValue(T maximumValue);