Date in TIME_IN_MILLIS not serialized as number

[maxencelaurent]

Describe the bug
According to jsonb-api (JsonbDateFormat#TIME_IN_MILLIS), a date formatted with the TIME_IN_MILLIS formatter shall be serialized as a number. This is not the case. Such dates are serialized as strings.

Explicit conversion to string is made here:

yasson/src/main/java/org/eclipse/yasson/internal/serializer/AbstractDateTimeSerializer.java

Line 67 in e7ff427

return String.valueOf(toInstant(object).toEpochMilli());

Then, this string is escaped when writing the JSON object in JsonGenerator#write(String).

To Reproduce
Serialize an instance of:

public class Dummy {

    @JsonbDateFormat(value = JsonbDateFormat.TIME_IN_MILLIS)
    private OffsetDateTime date;

    public OffsetDateTime getDate(){ return date;}
    public void setDate(OffsetDateTime date){  this.date = date;}
}

The JSON will looks like

{ "date": "1638953417522" }

Expected behavior

JSON should looks like

{ "date": 1638953417522 }

System information:

• OS: Linux
• Java Version: 11
• Yasson Version: 2.0.4

Additional context
Deserialization works fine, with both representation:

{ "date": 1638953417522 }

{ "date": "1638953417522" }

[Verdent]

Hi @maxencelaurent , thank you for reaching out. This really seems like a bug. Thank you for reporting this. I will take a look at it.

[abimarank]

Hi @Verdent, Are you working on this issue? If not, I planned to provide the fix.

[Verdent]

Hi @abimarank , I did not yet started. Feel free to do it :-) Thank you