[java-firestore] CustomClassMapper.convertBigDecimal calls .abs() on Double, unintentionally flipping negative values to positive

[hritikpgupta]

Environment

• Artifact: com.google.cloud:google-cloud-firestore (also used via com.google.firebase:firebase-admin)
• Affected Versions: 3.21.1 through 3.48.0 (latest)
• File: com.google.cloud.firestore.encoding.CustomClassMapper.java

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Describe the Bug

When deserializing a Firestore document containing a negative floating point number into a Java POJO field of type java.math.BigDecimal using DocumentSnapshot.toObject(Class<T>), the negative value is converted to a positive number.

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Offending Code

In com.google.cloud.firestore.encoding.CustomClassMapper.java :

private static BigDecimal convertBigDecimal(Object o, DeserializeContext.ErrorPath errorPath) {
    if (o instanceof Integer) {
        return BigDecimal.valueOf(((Integer) o).intValue());
    } else if (o instanceof Long) {
        return BigDecimal.valueOf(((Long) o).longValue());
    } else if (o instanceof Double) {
        return BigDecimal.valueOf(((Double) o).doubleValue()).abs(); // <--- Calls .abs()
    } else if (o instanceof BigDecimal) {
        return (BigDecimal) o;
    } else if (o instanceof String) {
        return new BigDecimal((String) o);
    } else {
        throw errorPath.deserializeError(
            "Failed to convert a value of type " + o.getClass().getName() + " to BigDecimal");
    }
}