REST Receiver Adapter Configure array type

Hi Friends,

I have the next integration:

SAP ECC-->PI-->JSON SERVICES

I have configured my scenario correctly, but I have a problem with the " [ ] "

I need the end json expression of this form:

"Values": [

[ "val1","val2","val3" ]

]

but I get:

"Values": [ "val1","val2","val3" ]

I can´t create the [ ] without give them a name.

Can you help me with this problem? how I must create this expression [ ] without give a name on the data type... must convert on the com. Channel rest?