Jackson deserialize ISO8601 formatted date-time into Java8 Instant

If you want to serialize Date objects into ISO-8601, you don't need to specify a pattern at all - ISO-8601 is the default pattern. It is kind of mentioned in the JsonFormat Java doc:

Common uses include choosing between alternate representations -- for example, whether Date is to be serialized as number (Java timestamp) or String (such as ISO-8601 compatible time value) -- as well as configuring exact details with pattern() property.

[emphasasis mine] you should understand from the above text that specifying shape = STRING would mean an ISO-8601 format but you can choose something else using the pattern property.

In my experience, this always turns out a UTC date format (with the time zone rendered as +0000), which could be the default time zone in my VM (even though my operating system clock is not set to UTC).

In Jackson 2.9.8 (current one as I'm writing this) it's better to use Instant instead of Date.

You have to add a dependency:

<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-jsr310</artifactId>
    <version>2.9.8</version>
</dependency> 

Also, register the module and configure SerializationFeature.WRITE_DATES_AS_TIMESTAMPS to false.

new ObjectMapper()
                .findAndRegisterModules()
                .configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);

More information about Jackson for Java8 here: https://github.com/FasterXML/jackson-modules-java8

You need to set the explicit time zone via XXX in your modell class:

@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd'T'HH:mm:ss.SSSXXX")

(see: https://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html)