public class Hilo extends Thread {
        @Override
        public void run() {
            while(true) {
                try {
                    Thread.sleep(2000);
                    UI.getCurrent().access(new Runnable() {
                        @Override
                        public void run() {
                            labelHora.setValue("Ahora: "+Instant.now());
                        }                        
                    });              
                }catch(InterruptedException ez) {
                    ez.printStackTrace();
                }
            }
        }      
}

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>

   <groupId>com.guayoyolabs.goliat</groupId>
   <artifactId>goliat-webapp</artifactId>
   <packaging>pom</packaging>
   <version>1.0-SNAPSHOT</version>
   <name>goliat-webapp-parent</name>

   <properties>
   	<vaadin.version>8.0.4</vaadin.version>
   	<vaadin.plugin.version>8.0.4</vaadin.plugin.version>
   	<jetty.plugin.version>9.2.3.v20140905</jetty.plugin.version>
   	<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   	<maven.compiler.source>1.8</maven.compiler.source>
   	<maven.compiler.target>1.8</maven.compiler.target>
   </properties>

   <build>
   	<plugins>
   		<plugin>
   			<groupId>org.apache.maven.plugins</groupId>
   			<artifactId>maven-compiler-plugin</artifactId>
   			<version>3.0</version>
   		</plugin>
   		<plugin>
   			<groupId>org.apache.maven.plugins</groupId>
   			<artifactId>maven-resources-plugin</artifactId>
   			<version>2.6</version>
   		</plugin>
   	</plugins>
   	<pluginManagement>
   		<plugins>
   			<plugin>
   				<groupId>org.apache.maven.plugins</groupId>
   				<artifactId>maven-war-plugin</artifactId>
   				<version>3.0.0</version>
   				<configuration>
   					<failOnMissingWebXml>false</failOnMissingWebXml>
   				</configuration>
   			</plugin>
   			<plugin>
   				<groupId>com.vaadin</groupId>
   				<artifactId>vaadin-maven-plugin</artifactId>
   				<version>${vaadin.plugin.version}</version>
   			</plugin>
   			<plugin>
   				<groupId>org.apache.maven.plugins</groupId>
   				<artifactId>maven-jar-plugin</artifactId>
   				<version>2.5</version>
   			</plugin>
   			<plugin>
   				<groupId>org.apache.maven.plugins</groupId>
   				<artifactId>maven-source-plugin</artifactId>
   				<version>2.4</version>
   			</plugin>
   		</plugins>
   	</pluginManagement>
   </build>

   <dependencyManagement>
   	<dependencies>
   		<dependency>
   			<groupId>javax.servlet</groupId>
   			<artifactId>javax.servlet-api</artifactId>
   			<version>3.0.1</version>
   			<scope>provided</scope>
   		</dependency>
   		<dependency>
   			<groupId>com.vaadin</groupId>
   			<artifactId>vaadin-bom</artifactId>
   			<version>${vaadin.version}</version>
   			<type>pom</type>
   			<scope>import</scope>
   		</dependency>
   	</dependencies>
   </dependencyManagement>

   <repositories>
   	<repository>
   		<id>vaadin-addons</id>
   		<url>http://maven.vaadin.com/vaadin-addons</url>
   	</repository>
   </repositories>

   <profiles>
   	<profile>
   		<!-- Vaadin pre-release repositories -->
   		<id>vaadin-prerelease</id>
   		<activation>
   			<activeByDefault>false</activeByDefault>
   		</activation>

   		<repositories>
   			<repository>
   				<id>vaadin-prereleases</id>
   				<url>http://maven.vaadin.com/vaadin-prereleases</url>
   			</repository>
   			<repository>
   				<id>vaadin-snapshots</id>
   				<url>https://oss.sonatype.org/content/repositories/vaadin-snapshots/</url>
   				<releases>
   					<enabled>false</enabled>
   				</releases>
   				<snapshots>
   					<enabled>true</enabled>
   				</snapshots>
   			</repository>
   		</repositories>
   		<pluginRepositories>
   			<pluginRepository>
   				<id>vaadin-prereleases</id>
   				<url>http://maven.vaadin.com/vaadin-prereleases</url>
   			</pluginRepository>
   			<pluginRepository>
   				<id>vaadin-snapshots</id>
   				<url>https://oss.sonatype.org/content/repositories/vaadin-snapshots/</url>
   				<releases>
   					<enabled>false</enabled>
   				</releases>
   				<snapshots>
   					<enabled>true</enabled>
   				</snapshots>
   			</pluginRepository>
   		</pluginRepositories>
   	</profile>
   </profiles>
 <modules>
   <module>goliat-webapp-widgetset</module>
   <module>goliat-webapp-backend</module>
   <module>goliat-webapp-ui</module>
   <module>goliat-webapp-production</module>
 </modules>
</project>`

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>goliat-webapp</artifactId>
        <groupId>com.guayoyolabs.goliat</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>goliat-webapp-widgetset</artifactId>
    <name>goliat-webapp-widgetset</name>
    <packaging>jar</packaging>

    <dependencies>
        <!-- Versions for these are configured in the parent POM -->
        <dependency>
			<groupId>com.vaadin</groupId>
			<artifactId>vaadin-charts</artifactId>
			<version>4.0.0</version>
		</dependency>
		<dependency>
			<groupId>com.vaadin</groupId>
			<artifactId>vaadin-push</artifactId>
		</dependency>
        <dependency>
            <groupId>com.vaadin</groupId>
            <artifactId>vaadin-client</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>com.vaadin</groupId>
            <artifactId>vaadin-client-compiler</artifactId>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>com.vaadin</groupId>
                <artifactId>vaadin-maven-plugin</artifactId>
                <configuration>
                    <extraJvmArgs>-Xmx512M -Xss1024k</extraJvmArgs>
                    <webappDirectory>${basedir}/target/classes/VAADIN/widgetsets</webappDirectory>
                    <draftCompile>true</draftCompile>
                    <compileReport>false</compileReport>
                    <!-- Change to PRETTY (or possibly DETAILED) to get
                    unobfuscated client side stack traces. A better approach
                    for debugging is to use Super Dev Mode -->
                    <style>OBF</style> 
                    <strict>true</strict>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>update-widgetset</goal>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-source-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>jar</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <configuration>
                    <archive>
                        <manifestEntries>
                            <Vaadin-Package-Version>1</Vaadin-Package-Version>
                            <Vaadin-Widgetsets>com.guayoyolabs.goliat.GoliatWidgetset</Vaadin-Widgetsets>
                        </manifestEntries>
                    </archive>
                    <!-- Exclude some unnecessary files generated by the 
                        GWT compiler. -->
                    <excludes>
                        <exclude>VAADIN/gwt-unitCache/**</exclude>
                        <exclude>VAADIN/widgetsets/WEB-INF/**</exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>