google-cloud-java: NoClassDefFoundError: com/google/api/gax/retrying/RetrySettings at LanguageServiceSettings

Hi I’ve created a java class with a main method in order to test NLP API.

Extract of my pom.xml:

	<!-- Google Cloud Natural Language API -->
	<dependency>
		<groupId>com.google.cloud</groupId>
		<artifactId>google-cloud-language</artifactId>
		<version>0.19.0-beta</version>
	</dependency>

In my GoogleTest java class I test others google APIs.

My method:

public static void myNaturalLanguageTest() throws IOException {
	
	//Instanciate a client
	LanguageServiceClient language = LanguageServiceClient.create();

	//Text to analyze
	String text = "Hello world";
	Document doc = Document.newBuilder().setContent(text).setType(Type.PLAIN_TEXT).build();

	//Detect the sentiment
	//TODO we obtained an error for the moment - 29-03-2017
	//java.lang.NoSuchMethodError: com.google.common.util.concurrent.MoreExecutors.directExecutor()Ljava/util/concurrent/Executor;
	Sentiment sentiment = language.analyzeSentiment(doc).getDocumentSentiment();

	System.out.printf("Text: %s%n", text);
	System.out.printf("Sentiment: %s, %s%n", sentiment.getScore(), sentiment.getMagnitude());
}

When I execute my java class, I obtain a NoCLassDefFoundError:

Exception in thread "main" java.lang.NoClassDefFoundError: com/google/api/gax/retrying/RetrySettings
	at com.google.cloud.language.spi.v1.LanguageServiceSettings$Builder.<clinit>(LanguageServiceSettings.java:245)
	at com.google.cloud.language.spi.v1.LanguageServiceSettings.defaultBuilder(LanguageServiceSettings.java:189)
	at com.google.cloud.language.spi.v1.LanguageServiceClient.create(LanguageServiceClient.java:114)
	at com.xxx.product.xxx.google.test.GoogleTest.myNaturalLanguageTest(GoogleTest.java:396)
	at com.xxx.product.moderation.google.test.GoogleTest.main(GoogleTest.java:259)
Caused by: java.lang.ClassNotFoundException: com.google.api.gax.retrying.RetrySettings
	at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
	... 5 more

Thanks.