code: private static EmbeddedJettyConfiguration extractConfiguration(Class<?> klass) {
  		final AbstractConfiguration configuration = findConfiguration(klass);
  
  		if (configuration == null) {
  			return null;
  		}
  
  		if (!(configuration instanceof EmbeddedJettyConfiguration)) {
  			throw new IllegalJettyConfigurationException();
  		}
  
  		return (EmbeddedJettyConfiguration) configuration;
  	}
docs: Try to extract {@link EmbeddedJetty} configuration from the test class: search for a static
  field/method annotated with {@link com.github.mjeanroy.junit.servers.annotations.TestServerConfiguration}).
  
  @param klass The test class.
  @return The {@link EmbeddedJetty} configuration.
  @throws IllegalJettyConfigurationException If extracted annotation is not an instance of {@link EmbeddedJetty}.