override subflow input attr when restart main flow

[unysun]

Current behavior (how does the issue manifest):
hi,
when i restart flow which include subflow and has same name activity in main flow and sub flow by FlowTesterService, i got
all same name activity attribute override, for exp:
in main flow, i have a activity called log_2,
in subfow_1 flow, i have a activity called log_2 too.

when i restart flow by curl:
curl "http://127.0.0.1:8080/flow/restart"
-v
-H "Content-Type: application/json"
-X POST
-d '{"initialState":{"flowURI":"res://flow:main","status":100,"tasks":[{"id":"log_2","status":20}],"id":"123430d67b9264a4c77b6a80e935e513","workQueue":[{"id":1,"subflowId":0,"taskId":"log_2"}]},"interceptor":{"tasks":[{"id":"log_2","inputs":{"message":"E","addDetails":false,"usePrint":false}}]}}'

all log_2 output message become "E", but in subflow_1, i set "C" in log_2

Expected behavior:
not override all same name activity in deferent flow,

Minimal steps to reproduce the problem (not required if feature enhancement):

Please tell us about your environment (Operating system, docker version, browser & web ui version, etc):
mac os

Flogo version (CLI & contrib/lib. If unknown, leave empty or state unknown): 0.X.X
latest

Additional information you deem important (e.g. issue happens only occasionally):