DateTimeSerializer should take the configured time zone into account

[pavax]

At the moment the com.fasterxml.jackson.datatype.joda.ser.DateTimeSerializer writes the following code if the WRITE_DATES_AS_TIMESTAMPS feature is disabled:
...
jgen.writeString(value.toString());
...
whereas value is the DateTime object. However this doesn't take the configured timezone into account which might be set in ObjectMapper.setTimeZone(TimeZone timeZone).

A similar Issue was fixed for the DateTimeDeserializer see: #14

[cowtowncoder]

Fixed for 2.3.1.

[Macarse]

@cowtowncoder This change was not mentioned in https://github.com/FasterXML/jackson/wiki/Jackson-Release-2.3.1

[cowtowncoder]

@Macarse thanks, added it there.