Why does consuming a RESTful web service (using javax.ws.rs.* and Jsersey) work in unit test but not when submitted to Spark?

I have a piece of code that runs inside Spark Streaming and tries to get some data from a RESTful web service. The code snippet in question is:

 Client client = ClientBuilder.newClient();
 WebTarget target = client.target("http://localhost:2222/rest");
 target = target.path("annotate")
             .queryParam("text", UrlEscapers.urlFragmentEscaper().escape(spotlightSubmission))
             .queryParam("confidence", "0.3");

 logger.warn("!!! DEBUG !!! target: {}", target.getUri().toString());

 String response = target.request().accept(MediaType.APPLICATION_JSON_TYPE).get(String.class);

 logger.warn("!!! DEBUG !!! Spotlight response: {}", response);

When run inside a unit test as follows:

 mvn clean test -Dtest=SpotlightTest#testCountWords

it contacts the RESTful web service and retrieves some data as expected. But when the same code is run as part of the application that is submitted to Spark, using spark-submit script, I receive the following error:

  java.lang.NoSuchMethodError: javax.ws.rs.core.MultivaluedMap.addAll(Ljava/lang/Object;[Ljava/lang/Object;)V

as soon as it tries to run:

String response = target.request().accept(MediaType.APPLICATION_JSON_TYPE).get(String.class);

I'm using Spark 1.1.0 and for consuming the web service I'm using Jersey in my project's pom.xml:

 <dependency>
  <groupId>org.glassfish.jersey.containers</groupId>
  <artifactId>jersey-container-servlet-core</artifactId>
  <version>2.14</version>
</dependency>

So I suspect that when the application is submitted to Spark, somehow there's a different JAR in the environment that uses a different version of Jersey / javax.ws.rs.*

Does anybody know which version of Jersey / javax.ws.rs.* is used in the Spark environment, or how to solve this conflict?