Spring Boot provides integration with three JSON mapping libraries:
Jackson is the preferred and default library.
Auto-configuration for Jackson is provided and Jackson is part of spring-boot-starter-json.
When Jackson is on the classpath an ObjectMapper bean is automatically configured.
Several configuration properties are provided for customizing the configuration of the ObjectMapper.
Auto-configuration for Gson is provided.
When Gson is on the classpath a Gson bean is automatically configured.
Several spring.gson.* configuration properties are provided for customizing the configuration.
To take more control, one or more GsonBuilderCustomizer beans can be used.