the mutation is
{
set {
<0x3de2597b8> <valid> "true" .
}
}
really simple, and it is works fine in Ratel.
the error is
{
"errors": [
{
"message": "Error parsing JSON at line 2, character 6: invalid character 's' looking for beginning of object key string\n",
"extensions": {
"code": "ErrorInvalidRequest"
}
}
]
}