parameter: expression - ="${project}"

required:
readonly:

 public  void execute() throws MojoExecutionException 
{
        try {
            setSystemProperties();
            getLog().info("Loading broker configUri: " + configUri);
            final BrokerService broker = BrokerFactory.createBroker(configUri);
            if (fork) {
                new Thread(new Runnable() {
                    public void run() {
                        try {
                            broker.start();
                            waitForShutdown(broker);
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                    }
                }).start();
            } else {
                broker.start();
                waitForShutdown(broker);
            }
        } catch (Exception e) {
            throw new MojoExecutionException("Failed to start ActiveMQ Broker", e);
        }
}

 protected  void setSystemProperties() 
{
        // Set the default properties
        System.setProperty("activemq.base", project.getBuild().getDirectory() + "/");
        System.setProperty("activemq.home", project.getBuild().getDirectory() + "/");
        System.setProperty("org.apache.activemq.UseDedicatedTaskRunner", "true");
        System.setProperty("org.apache.activemq.default.directory.prefix", project.getBuild().getDirectory() + "/");
        System.setProperty("derby.system.home", project.getBuild().getDirectory() + "/");
        System.setProperty("derby.storage.fileSyncTransactionLog", "true");
        // Overwrite any custom properties
        System.getProperties().putAll(systemProperties);
}

Set system properties

 protected  void waitForShutdown(BrokerService broker) throws Exception 
{
        final boolean[] shutdown = new boolean[] {
            false
        };
        Runtime.getRuntime().addShutdownHook(new Thread() {
            public void run() {
                synchronized (shutdown) {
                    shutdown[0] = true;
                    shutdown.notify();
                }
            }
        });
        // Wait for any shutdown event
        synchronized (shutdown) {
            while (!shutdown[0]) {
                try {
                    shutdown.wait();
                } catch (InterruptedException e) {
                }
            }
        }
        // Stop broker
        broker.stop();
}

Wait for a shutdown invocation elsewhere