code: private static String getAttributeValue(final Element element, final String attributeName, final boolean mandatory)
              throws PluginConfigurationException {
          String returnValue = element.attributeValue(attributeName);
  
          if (mandatory) {
              if (StringUtils.isBlank(returnValue)) {
                  throw new PluginConfigurationException("Error loading plugin package : mandatory attribute " + attributeName + " not found");
  
              }
          }
  
          return returnValue;
      }
docs: Returns the value of the given attribute name of element. If mandatory is
  <code>true</code> and the attribute is blank or null, an exception is
  thrown.
  
  @param element
  The element whose attribute must be read
  @param attributeName
  The attribute name
  @param mandatory
  <code>true</code> if the attribute is mandatory
  
  
  @return the attribute value * @throws PluginConfigurationException
  if the attribute can't be found or is blank