/** Ensure able to initialise with <code>null</code> value. */
  public void testInitialiseWithNullValue() {
    this.properties.addProperty("blank", null);

    // Initialise from properties
    SourcePropertiesImpl clone = new SourcePropertiesImpl(this.properties);

    // Ensure null value loaded
    Properties props = clone.getProperties();
    assertTrue("Ensure load null value", props.keySet().contains("blank"));
  }