The Server log snippet shows that the Data Adapter fills the maps with nulls, despite it reads data from an external file.
As you suggest, maybe the RSS3.xml is in the wrong place and maybe "ReadData" does not throw an exception for this.
Can you confirm this by debugging your "run" method?

In fact, in order to access external files, your Data Adapter should refer to the "configDir" File argument it receives in the "init" method, which contains the absolute path to the directory where the related "adapters.xml" file resides
You should never use relative pathnames, but rather absolute pathnames that you can build based on "configDir".
Hence, you should put RSS3.xml beside "adapters.xml" or in a subfolder and build an absolute pathname for it.