Value parse problem with user defined data in a property bag

[liufang-robot]

Hello, I have a problem...
When I try to add a user defined type data in a property bag, the value parse will get an error with the user data.

Here is an example:
Create a simple data structure:.

struct UserData
{
   /** Contains a sequence of doubles. */
   std::vector<double> samples;
   std::string name;
   int id;
};

create the typekit by typegen (or manually).
add the UserData property instance in a component (simply named 'hello'):

/// user_data_, user_data_in_bag_ are UserData type members of hello component.
/// test_bag_ is PropertyBag type member of hello component

/// in the constructor of component.
/// add a UserData type data as a plain property.
addProperty("user_data", user_data_)
/// add a UserData type data in a propertybag.
test_bag_.addProperty("user_data",user_data_in_bag_);
addProperty("test_bag",test_bag_);

And the ValueParser will not handle the propertybag case correctly.
we can simple use deployer to check(deployer use rtt scripting ValueParser to get the value).
In a deployer:

# input this and enter, try to get the id value. this is OK
hello.user_data.id

# input this and enter, try to get the id value.  this is Not OK
hello.test_bag.user_data.id
# It gives an error:
Semantic error: Property test_bag not present in PropertyBag test_bag in hello.

The error is logged in scripting/ValueParser.cpp line 168.
I looked into the code and found it seems that the case a user defined data in a property bag is never considered.
In the code, it only try to recursively use a propertybag to analysis the expression.
Is this true?
Thanks for your reply.