code: private static PropertyDescriptor getPropertyDescriptorOptional(
          Class<?> beanClass, String propertyName)
      {
          List<PropertyDescriptor> propertyDescriptors = 
              getPropertyDescriptorsOptional(beanClass);
          for (PropertyDescriptor propertyDescriptor : propertyDescriptors)
          {
              if (propertyDescriptor.getName().equals(propertyName))
              {
                  return propertyDescriptor;
              }
          }
          return null;
      }
docs: Returns the PropertyDescriptor with the given name from the given
  bean class, or <code>null</code> if there is no such property
  
  @param beanClass The bean class
  @param propertyName The property name
  @return The PropertyDescriptor