Issue with correctly encoding operational model data

[111pontes]

In YDK-Py 0.5.4, filter data is ignored by parent objects. For example, the following code attempts to only read BGP neighbor data:

bgp = xr_ipv4_bgp_oper.Bgp()  # create filter object

instance = bgp.instances.Instance()
instance.instance_name = "default"
neighbor = instance.instance_active.default_vrf.neighbors.Neighbor()
instance.instance_active.default_vrf.neighbors.neighbor.append(neighbor)
bgp.instances.instance.append(instance)

# read data from NETCONF device
bgp = crud.read(provider, bgp)

Instead, it retrieves all data:

2017-05-22 10:18:54,857 - ydk.providers._provider_plugin - DEBUG - 
<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="urn:uuid:a78c4ef5-d8a5-416e-a7c2-ec859b2f2fab">
  <get>
    <filter type="subtree">
      <bgp xmlns="http://cisco.com/ns/yang/Cisco-IOS-XR-ipv4-bgp-oper"/>
    </filter>
  </get>
</rpc>

Specifying, the most specific object can be used as a workaround:

neighbor = crud.read(provider, bgp.instances.instance[0].instance_active.default_vrf.neighbors.neighbor[0])

[ghost]

The issue seems that the 0.5.4 encoder cannot encode any operational data. For example, using openconfig-bgp.Bgp class, the state data is left out when creating the payload :

from ydk.models.openconfig.openconfig_bgp import Bgp
from ydk.providers import CodecServiceProvider
from ydk.services import CodecService

codec=CodecService()
codec_p=CodecServiceProvider(type='xml')

f = Bgp()
q = Bgp.Neighbors.Neighbor()
q.neighbor_address = '1.2.3.4'
q.state.description='test'
f.neighbors.neighbor.append(q)
codec.encode(codec_p,f)

Encoding operation initiated
Result of encoding: 
<bgp xmlns="http://openconfig.net/yang/bgp">
  <neighbors>
    <neighbor>
      <neighbor-address>1.2.3.4</neighbor-address>
    </neighbor>
  </neighbors>
</bgp>

Confirmed that this issue is not there in ydk 0.6.0-alpha for this model. Also tested Cisco-IOS-XR-ipv4-bgp-oper and encoding seems to work fine there

 print(codec.encode(codec_p,f))

<bgp xmlns="http://openconfig.net/yang/bgp">
  <neighbors>
    <neighbor>
      <neighbor-address>1.2.3.4</neighbor-address>
      <state>
        <description>test</description>
      </state>
    </neighbor>
  </neighbors>
</bgp>

[ghost]

The problem is this line which is present in all of the generated model APIs. If the container/list is not config, we are always returning False in _has_data().