“End of file” or EOF means that the socket, here TCP connection, closed. Since the ConfD developer log and the Java application client side both report that the connection was closed, it seems like a TCP communication issue between them, not an issue with the application or ConfD.
You can simulate the connection issue as described previously in this post: Control socket closed with error -2 and then ConfD client exit with "INTERNAL ERROR" - #4 by cohult