vaadin addon maven plugin compilation error

I am using refresher addon. To compile it i am using below mentioned plugin.

<build>
		<plugins>
			<plugin>
				<groupId>org.codehaus.mojo</groupId>
				<artifactId>gwt-maven-plugin</artifactId>
				<version>2.1.0-1</version>
				<configuration>
					<webappDirectory>${project.build.directory}/${project.build.finalName}/VAADIN/widgetsets</webappDirectory>
					 <webappDirectory>src/main/webapp/VAADIN/widgetsets </webappDirectory> 
				</configuration>
				<executions>
					<execution>
					<configuration>
                        <modules>
                            <module><package structure>.FormLayoutWidgetset</module>
                        </modules>                       
                     </configuration>
						<goals>
							<goal>resources</goal>
							<goal>compile</goal>
						</goals>
					</execution>
				</executions>
			</plugin>
			<plugin>
				<groupId>com.vaadin</groupId>
				<artifactId>vaadin-maven-plugin</artifactId>
				<version>1.0.1</version>
				<executions>
					<execution>
					 <configuration>
                        <modules>
                            <module><package structure>.FormLayoutWidgetset</module>
                        </modules>                       
                     </configuration>
					<goals>
						<goal>update-widgetset</goal>
					</goals>
					</execution>
				</executions>
			</plugin>
		</plugins>
	</build>

Note: FormLayoutWidgetset.gwt.xml is present inside

Compilation is not happening and it is giving below mentioned error.

ERROR] Oct 16, 2012 7:17:41 AM com.vaadin.terminal.gwt.widgetsetutils.ClassPathExplorer getAvailableWidgetSets
[ERROR]
 INFO: Search took 62ms
[ERROR]
 Exception in thread "main" java.io.FileNotFoundException: \<package structure>\FormLayoutWidgetset.gwt.xml (Access is denied)
[ERROR]
 at java.io.FileOutputStream.open(Native Method)
[ERROR]
 at java.io.FileOutputStream.<init>(FileOutputStream.java:212)
[ERROR]
 at java.io.FileOutputStream.<init>(FileOutputStream.java:104)
[ERROR]
 at com.vaadin.terminal.gwt.widgetsetutils.WidgetSetBuilder.commitChanges(WidgetSetBuilder.java:157)
[ERROR]
 at com.vaadin.terminal.gwt.widgetsetutils.WidgetSetBuilder.updateWidgetSet(WidgetSetBuilder.java:139)
[ERROR]
 at com.vaadin.terminal.gwt.widgetsetutils.WidgetSetBuilder.main(WidgetSetBuilder.java:52)

Please let me know what is wrong here??