modules/spring-mock-mvc/src/main/java/io/restassured/module/mockmvc/specification/MockMvcRequestSpecBuilder.java
public MockMvcRequestSpecBuilder setBody(Object object, ObjectMapperType mapperType) {
        spec.body(object, mapperType);
        return this;
    }
public MockMvcRequestSpecBuilder setBody(Object object, ObjectMapperType mapperType) {
        spec.body(object, mapperType);
        return this;
    }
Specify an Object request content that will automatically be serialized to JSON or XML and sent with the request using a specific object mapper type.
This works for the POST, PATCH and PUT methods only. Trying to do this for the other http methods will cause an exception to be thrown.
<p>
Example of use:
<pre>
Message message = new Message();
message.setMessage("My beautiful message");

given().
body(message, ObjectMapper.GSON).
expect().
content(equalTo("Response to a beautiful message")).
when().
post("/beautiful-message");
</pre>
</p>
Note that {@link #setBody(Object, ObjectMapperType)}
are the same except for the syntactic difference.
</p>

@param object     The object to serialize and send with the request
@param mapperType The object mapper type to be used
@return The request specification