My problem discussed here in the lines above and in the separate thread is solved, after usage the latest java version from oracle, available for my RaspPi.
But there is an existing problem with the 2.1.0-binding, if the response JSON contains a NULL value instead a price. In this case you have to switch to the snapshot version 2.2.
A big thanks fly out to @opus and @martinvw for the support, hints and patience with me.