@Test
    public void testJsonSchemaCacheSizeFromConfigFile() throws URISyntaxException, IOException {
        URL url = Objects.requireNonNull(getClass().getResource("/connect-test.properties"));
        File propFile = new File(url.toURI());
        String workerPropsFile = propFile.getAbsolutePath();
        Map<String, String> workerProps = !workerPropsFile.isEmpty() ?
                Utils.propsToStringMap(Utils.loadProps(workerPropsFile)) : Collections.emptyMap();

        JsonConverter rc = new JsonConverter();
        rc.configure(workerProps, false);
    }
When schemas are disabled, fields are mapped to Connect maps.
connect/json/src/test/java/org/apache/kafka/connect/json/JsonConverterTest.java