@JsonFormat is ignored by the DateSerializer unless either a custom pattern or a timezone are specified

[aseovic]

If the user simply specifies @JsonFormat annotation with string shape, the shape is ignored and the date is serialized as long:

static class Person
{
    @JsonFormat(shape = JsonFormat.Shape.STRING)
    public Date dateOfBirth;
}

gets serialized as:

{"dateOfBirth":1198800000000}

I believe the correct behavior should be to write the date as a string in ISO8601 format.

If you agree I will implement the fix and create a PR for it.

[cowtowncoder]

@aseovic yes that looks like a bug, PR would be great.