def acquire_token_for_client(resource, client_cred)
      fail_if_arguments_nil(resource, client_cred)
      token_request_for(client_cred).get_for_client(resource)
    end
def acquire_token_for_client(resource, client_cred)
      fail_if_arguments_nil(resource, client_cred)
      token_request_for(client_cred).get_for_client(resource)
    end
Gets an access token with only the clients credentials and no user
 information.

 @param String resource
   The resource being requested.
 @param ClientCredential|ClientAssertion|ClientAssertionCertificate
   An object that validates the client application by adding
   #request_params to the OAuth request.
 @return TokenResponse