title: Cucumber Scenario : giving an empty String as value of parameter in a scenario step
body: <p>I have a step implemented like this:</p>
  
  <pre><code>@When("I add an attribute named '(.+)' with unit '(.+)' to the item named '(.+)'")
  public void addAttributeToAndItem(String attributeName, String unitName, String itemName){
       .....
  }
  </code></pre>
  
  <p>in my Cucumber Scenario, i would like to add and attribute not having a unit, so the value of "unit name" should be and empty String. how can I specify this empty String in to my Scenario step.</p>
  
  <p>I tried this one:</p>
  
  <pre><code>    Scenario: add attribute to an item
          When  I add an attribute named 'Color' with unit ' ' to the item named ' Car'
  </code></pre>
  
  <p>but it does not work. The ' ' is always seem as a value (a space) and not an empty string. please can somebody help me?</p>