Add expanded annotation to Parameter and related implementations

src/main/java/org/scijava/command/CommandModuleItem.java

@@ -139,6 +139,11 @@ public String getWidgetStyle() {
 	public String getWidgetGroup() {
 		return getParameter().group();
 	}
+
+	@Override
+	public boolean isExpanded() {
+		return getParameter().expanded();
+	}
 
 	@Override
 	public T getMinimumValue() {

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

@@ -75,6 +75,7 @@ public String toString() {
 		sm.append("callback", getCallback());
 		sm.append("widgetStyle", getWidgetStyle());
 		sm.append("widgetGroup", getWidgetGroup());
+		sm.append("expanded", isExpanded());
 		sm.append("default", getDefaultValue());
 		sm.append("min", getMinimumValue());
 		sm.append("max", getMaximumValue());
@@ -237,6 +238,11 @@ public String getWidgetStyle() {
 	public String getWidgetGroup() {
 		return null;
 	}
+
+	@Override
+	public boolean isExpanded() {
+		return true;
+	}
 
 	@Override
 	public T getDefaultValue() {

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

@@ -60,6 +60,7 @@ public class DefaultMutableModuleItem<T> extends AbstractModuleItem<T>
 	private String callback;
 	private String widgetStyle;
 	private String widgetGroup;
+	private boolean expanded;
 	private T defaultValue;
 	private T minimumValue;
 	private T maximumValue;
@@ -96,6 +97,7 @@ public DefaultMutableModuleItem(final ModuleInfo info, final String name,
 		callback = super.getCallback();
 		widgetStyle = super.getWidgetStyle();
 		widgetGroup = super.getWidgetGroup();
+		expanded = super.isExpanded();
 		minimumValue = super.getMinimumValue();
 		maximumValue = super.getMaximumValue();
 		stepSize = super.getStepSize();
@@ -125,6 +127,7 @@ public DefaultMutableModuleItem(final ModuleInfo info,
 		callback = item.getCallback();
 		widgetStyle = item.getWidgetStyle();
 		widgetGroup = item.getWidgetGroup();
+		expanded = item.isExpanded();
 		minimumValue = item.getMinimumValue();
 		maximumValue = item.getMaximumValue();
 		softMinimum = item.getSoftMinimum();
@@ -188,6 +191,16 @@ public void setCallback(final String callback) {
 	public void setWidgetStyle(final String widgetStyle) {
 		this.widgetStyle = widgetStyle;
 	}
+
+	@Override
+	public void setWidgetGroup(final String widgetGroup) {
+		this.widgetGroup = widgetGroup;
+	}
+
+	@Override
+	public void setExpanded(final boolean expanded) {
+		this.expanded = expanded;
+	}
 
 	@Override
 	public void setDefaultValue(final T defaultValue) {
@@ -296,6 +309,11 @@ public String getWidgetStyle() {
 	public String getWidgetGroup() {
 		return widgetGroup;
 	}
+
+	@Override
+	public boolean isExpanded() {
+		return expanded;
+	}
 
 	@Override
 	public T getDefaultValue() {

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

@@ -159,6 +159,9 @@ public interface ModuleItem<T> extends BasicDetails {
 	 * the group.
 	 */
 	String getWidgetGroup();
+
+	/** Returns the state of the widget group, expanded and visible or not expanded and hidden. */
+	boolean isExpanded();
 
 	/** Gets the default value. */
 	T getDefaultValue();

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

@@ -61,6 +61,10 @@ public interface MutableModuleItem<T> extends ModuleItem<T> {
 	void setCallback(String callback);
 
 	void setWidgetStyle(String widgetStyle);
+
+	void setWidgetGroup(String widgetGroup);
+
+	void setExpanded(boolean expanded);
 
 	void setDefaultValue(T defaultValue);
 

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

@@ -92,6 +92,9 @@
 	 * output, such as a "verbose" flag.</li>
 	 * <li>MESSAGE: parameter value is intended as a message only, not editable by
 	 * the user nor included as an input or output parameter.</li>
+	 * <li>GROUP: parameter value specifies a widget group, not editable by
+	 * the user nor included as an input or output parameter. Members are added
+	 * to the group using the group parameter annotation.</li>
 	 * </ul>
 	 */
 	ItemVisibility visibility() default ItemVisibility.NORMAL;
@@ -145,6 +148,12 @@
 
 	/** Defines the widget group. */
 	String group() default "";
+
+	/** 
+	 * Defines the state of the widget group. When true the group is expanded and visible. 
+	 * Otherwise, group members are hidden.
+	 * */
+	boolean expanded() default true;
 
 	/** Defines the minimum allowed value (numeric parameters only). */
 	String min() default "";