private static String jsonConverterTypeName(String source) {
        int outerClassIndex = source.lastIndexOf('$');
        if (outerClassIndex == -1) {
            return  source + "JsonConverter";
        } else {
            return source.substring(0, outerClassIndex) + "JsonConverter$" +
                source.substring(outerClassIndex + 1) + "JsonConverter";
        }
    }
@param startVersion - the version we want to start at, inclusive
@param endVersion - the version we want to end at, exclusive
clients/src/test/java/org/apache/kafka/common/message/MessageTest.java