make object to json in js code example

Example 1: js create json from object

JSON.stringify(the_data);

Example 2: how to convert json to java object

Jackson Data-bind depdendency that take care of 
Converting between 
JSON to Java Object 
and 
Java Object to JSON

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.12.0</version>
</dependency>