old_contents: """
  Stored credentials.
  """
  from axiom import attributes, item
  from twisted.cred import credentials
  from zope import interface
  
  
  @interface.implementer(credentials.IUsernamePassword)
  class UsernamePassword(item.Item):
      """
      A stored username and password.
      """
      username = attributes.bytes(allowNone=False)
      password = attributes.bytes(allowNone=False)
  
new_contents: """
  Stored credentials.
  """
  from axiom import attributes, item
  from twisted.cred import credentials
  from zope import interface
  
  
  @interface.implementer(credentials.IUsernamePassword)
  class UsernamePassword(item.Item):
      """
      A stored username and password.
  
      Since the password is stored in plaintext, this is primarily useful for
      credentials you use, not for credentials you check against.
      """
      username = attributes.bytes(allowNone=False)
      password = attributes.bytes(allowNone=False)
  
subject: Add warning about plaintext credentials