Report a bug about timestamp data type

Hi Postgresql developers:

I have a question very need your confirmation. Here are the detail information.

Postgresql version: 9.4 version,

Language: Java,

IDE:Eclipse

Sql of the table :

CREATE TABLE vldlt (
id numeric(19,0) NOT NULL,
pwdexpireson timestamp without time zone
);

The sql to execute:

update vldlt set pwdexpireson = "2018-10-28 02:34:45.078+00" when id = "123"

Here are the steps to reproduce the issue:

First - use the java code below:

preparementStatement.setTimestamp(1,new Timestamp(new Date(System.currentTimeMillis()).getTime())) ;

Then - execute the preparementStatement.excuteUpdate() mehod to update the pwdexpireson field.

Finally - I get the statement is : update vldlt set pwdexpireson = "2018-10-28 02:34:45.078+00" :: date when id = "123" and the result will be displayed in Pgadmin tool is '2018-10-28 00:00:00' without millisecond.

I don't know how the why the data type is date, rather than timestamp. In addition, sometimes the result is date, but sometimes is timestamp.

I think it may be a bug for the check of timestamp data type for postgresql jdbc driver. Would you kindly give me some advice for this issue.

Best regard,

Tony