Databound datasource extension: issue with property

Hi community,

I recently tried to implement a datasource extension that consumes data from another datasource and manipulates it.

So I followed the developers guide and created a dataBuffer sdk extension. After adding a property of type ResultCellSet and implementing the corresponding getter/setter I logged the passed value in console. Surprisingly the setter got a selection string instead of the expected Data-Runtime-JSON. I tried a lot of the properties options but did not get any kind of Data-Runtime-JSON. 

property definition:

<property

     id="inputdata"

     type="ResultCellSet"
     title="Input Data"
     group="DataBinding">
    <option name="includeFormattedData"  value="true"/>
    <option name="includeMetadata"  value="true"/>
    <option name="fillMetadataProperty"  value="false"/>
    <option name="maxCells"  value="500"/>

</property>

example of the loggedValue passed to inputdata setter:

{"(MEASURES_DIMENSION)":"0D_NWI_NSAL","0CALMONTH":"12.009","0D_NWI_CHAN":["0","4","3"]}

I also noticed that there is a warning in the error log saying the following (even if a datasource is assigned):

The component "DS_3" does not have a data source. In this case, data-bound properties cannot use the "fillMetadataProperty" option.

It occurs when i change the configuration of the properties options so that 'fillMetadataProperty' is true and 'includeMetadata' is false.

The fact that this error occurs even though a datasource is assigned lets me assume that there is a bug that could maybe also influence the databinding of datasource extensions, resulting in my issue.

Did anyone successfully get the data-runtime-json in datasource extensions or experienced the same issue?