How to initialize WebDriver in Groovy Selenium

I am trying to initialize WebDriver with an instance of FireFoxDriver to do some automation.

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.firefox.FirefoxDriver;

WebDriver driver = new FirefoxDriver();

However, I am getting this error.

TestCase failed [java.lang.NoClassDefFoundError: Could not initialize class org.apache.http.conn.ssl.SSLConnectionSocketFactory:java.lang.NoClassDefFoundError: Could not initialize class org.apache.http.conn.ssl.SSLConnectionSocketFactory], time taken = 0

I am doing this script within SoapUI as a setup script, as this setup script will be use to initalize some header value. I have already dragged the selenium jar into the SoapUI/bin/ext folder and all of its lib jars.