presto-record-decoder/src/main/java/io/prestosql/decoder/json/JsonRowDecoder.java/JsonRowDecoder/JsonRowDecoder
class JsonRowDecoder:    JsonRowDecoder(ObjectMapper objectMapper, Map<DecoderColumnHandle, JsonFieldDecoder> fieldDecoders)
    {
        this.objectMapper = requireNonNull(objectMapper, "objectMapper is null");
        this.fieldDecoders = ImmutableMap.copyOf(fieldDecoders);
    }