The Kafka Connect JDBC Connector by default does not cope so well with:
NUMBER columns with no defined precision/scale. You may end up with apparent junk (bytes) in the output, or just errors. TIMESTAMP WITH LOCAL TIME ZONE. Throws JDBC type -102 not currently supported warning in the log. Read more about NUMBER data type in the Oracle docs.
tl;dr : How do I make it work? There are several options: