Jackson overcoming underscores in favor of camel-case

You can configure the ObjectMapper to convert camel case to names with an underscore:

objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);

Or annotate a specific model class with this annotation:

@JsonNaming(PropertyNamingStrategy.SnakeCaseStrategy.class)

Before Jackson 2.7, the constant was named:

PropertyNamingStrategy.CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES

If you want this for a Single Class, you can use the PropertyNamingStrategy with the @JsonNaming, something like this:

@JsonNaming(PropertyNamingStrategy.LowerCaseWithUnderscoresStrategy.class)
public static class Request {

    String businessName;
    String businessLegalName;

}

Will serialize to:

{
    "business_name" : "",
    "business_legal_name" : ""
}

Since Jackson 2.7 the LowerCaseWithUnderscoresStrategy in deprecated in favor of SnakeCaseStrategy, so you should use:

@JsonNaming(PropertyNamingStrategy.SnakeCaseStrategy.class)
public static class Request {

    String businessName;
    String businessLegalName;

}

If its a spring boot application, In application.properties file, just use

spring.jackson.property-naming-strategy=SNAKE_CASE

Or Annotate the model class with this annotation.

@JsonNaming(PropertyNamingStrategy.SnakeCaseStrategy.class)

You should use the @JsonProperty on the field you want to change the default name mapping.

class User{
    @JsonProperty("first_name")
    protected String firstName;
    protected String getFirstName(){return firstName;}
}

For more info: the API