Trailing zeros are stripped when deserializing BigDecimal values inside a @JsonUnwrapped property

[mjustin]

BigDecimal values within a @JsonUnwrapped property are stripping trailing zeros from the JSON source when deserialized. This differs from the behavior of a non-@JsonUnwrapped property, where the trailing zeroes are retained. I would expect the same behavior in both cases, and that ideally (for my use case) the trailing zeroes are retained.

I have confirmed this issue in the latest Jackson, version 2.11.1.

This appears to be the same issue as #632, which was filed against Jackson 2.4.0. I'm opening this as a new issue as requested.

From my tests, this appears to only affect deserialization, and not serialization.

Here is a JUnit 5 test that verifies this difference:

import com.fasterxml.jackson.annotation.JsonUnwrapped;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.junit.jupiter.api.Test;

import java.math.BigDecimal;

import static org.junit.jupiter.api.Assertions.assertEquals;

public class BigDecimalTrailingZeroesTest {
    private ObjectMapper objectMapper = new ObjectMapper();

    @Test
    public void bigDecimalTrailingZeroes() throws JsonProcessingException {
        // Passes
        assertEquals(new BigDecimal("5.00"),
                objectMapper.readValue("{\"value\": 5.00}", BigDecimalHolder.class).getValue());
    }

    @Test
    public void unwrappedBigDecimalTrailingZeroes() throws JsonProcessingException {
        // org.opentest4j.AssertionFailedError:
        // Expected :5.00
        // Actual   :5.0
        assertEquals(new BigDecimal("5.00"),
                objectMapper.readValue("{\"value\": 5.00}", NestedBigDecimalHolder.class).getHolder().getValue());
    }

    private static class BigDecimalHolder {
        private BigDecimal value;

        public BigDecimal getValue() {
            return value;
        }

        public void setValue(BigDecimal value) {
            this.value = value;
        }
    }

    private static class NestedBigDecimalHolder {
        @JsonUnwrapped
        private BigDecimalHolder holder;

        public BigDecimalHolder getHolder() {
            return holder;
        }

        public void setHolder(BigDecimalHolder holder) {
            this.holder = holder;
        }
    }
}

[cowtowncoder]

One quick note: I wonder if this might be due to buffering required by @JsonUnwrapped, perhaps similar to #2644. It is not exactly same issue but possible related.

[cowtowncoder]

Yes, I can reproduce this, will add a failing test. Most likely same problem as #2644, and same work-around applies here too: enable DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS.