title: Can not create a new client instance for ConfigCat (configcat-java-client-6.0.1)
body: <p>I want to implement config cat in my java 8 project.</p>
  <p>The way I am creating a config cat client is this:</p>
  <pre><code>import com.configcat.ConfigCatClient;
  public class ConfigCatClientUtil {
  
      public ConfigCatClientUtil() {
      }
  
      public ConfigCatClient createClient(String configCatKey) {
          ConfigCatClient configCatClient = null;
          try {
              configCatClient = new ConfigCatClient(configCatKey);
          } catch (Exception e) {
          }
          return configCatClient;
      }
  
  }
  </code></pre>
  <p>The problem is that when try to execute this <code>new ConfigCatClient(configCatKey)</code> throws an error:</p>
  <pre><code>messages Feb 11 13:11:38 server: Caused by: java.lang.NoClassDefFoundError: okhttp3/Callback
  </code></pre>
  <p>I am using <strong>configcat-java-client-6.0.1.jar</strong>.
  Does anyone know why I am getting this error?</p>