anchor.diff:                  <<"space_name">>, [], [], [{P1, 1000}]
               )),
               update(2, [<<"r2">>, <<"r1">>], P1, provider(<<"diginet rulz">>)),
  -            update(3, [<<"r2">>, <<"r1">>], U1, user(<<"onedata">>, [], []))
  +            update(3, [<<"r2">>, <<"r1">>], U1, user(<<"onedata">>, [], [], undefined))
           ]),
           expect_message([U1], 3, []),
   
  
positive.code: 
          push_update(Node, [
              update(3, [<<"r2">>, <<"r1">>], U1,
                  user(<<"onedata ftw">>, [], [S1])
              )
          ]),
          expect_message([U1], 3, [])
  
negative.code:                 <<"space_name">>, [{U1, Priv1}], [], []
              )),
              update(2, [<<"r2">>, <<"r1">>], P1, provider(<<"diginet rulz">>)),
              update(3, [<<"r2">>, <<"r1">>], U1, user(<<"onedata">>, [], [S1], S1))
          ]),
          expect_message([U1], 3, []),
  
  