@Test
    public void numericDecimalWithTrailingZerosToConnect() {
        BigDecimal reference = new BigDecimal(new BigInteger("15600"), 4);
        Schema schema = Decimal.schema(4);
        String msg = "{ \"schema\": { \"type\": \"bytes\", \"name\": \"org.apache.kafka.connect.data.Decimal\", \"version\": 1, \"parameters\": { \"scale\": \"4\" } }, \"payload\": 1.5600 }";
        SchemaAndValue schemaAndValue = converter.toConnectData(TOPIC, msg.getBytes());
        assertEquals(schema, schemaAndValue.schema());
        assertEquals(reference, schemaAndValue.value());
    }
When schemas are disabled, fields are mapped to Connect maps.
connect/json/src/test/java/org/apache/kafka/connect/json/JsonConverterTest.java