presto-ml/src/main/java/io/prestosql/plugin/ml/EvaluateClassifierPredictionsStateSerializer.java/EvaluateClassifierPredictionsStateSerializer/deserialize
class EvaluateClassifierPredictionsStateSerializer:    @Override
    public void deserialize(Block block, int index, EvaluateClassifierPredictionsState state)
    {
        Slice slice = VARCHAR.getSlice(block, index);
        Map<String, Map<String, Integer>> jsonState;
        try {
            jsonState = OBJECT_MAPPER.readValue(slice.getBytes(), new TypeReference<Map<String, Map<String, Integer>>>() {});
        }
        catch (IOException e) {
            throw new UncheckedIOException(e);
        }
        state.addMemoryUsage(slice.length());
        state.getTruePositives().putAll(jsonState.getOrDefault(TRUE_POSITIVES, ImmutableMap.of()));
        state.getFalsePositives().putAll(jsonState.getOrDefault(FALSE_POSITIVES, ImmutableMap.of()));
        state.getFalseNegatives().putAll(jsonState.getOrDefault(FALSE_NEGATIVES, ImmutableMap.of()));
    }