檢視MappingJackson2HttpMessageConverter原始碼註釋：

Implementation of {@link org.springframework.http.converter.HttpMessageConverter} that can read and
 * write JSON using <a href="http://wiki.fasterxml.com/JacksonHome">Jackson 2.x's</a> {@link ObjectMapper}.
 *
 * <p>This converter can be used to bind to typed beans, or untyped {@code HashMap} instances.
 *
 * <p>By default, this converter supports {@code application/json} and {@code application/*+json}
 * with {@code UTF-8} character set. This can be overridden by setting the
 * {@link #setSupportedMediaTypes supportedMediaTypes} property.
 *
 * <p>The default constructor uses the default configuration provided by {@link Jackson2ObjectMapperBuilder}.
 *
 * <p>Compatible with Jackson 2.9 and higher, as of Spring 5.0.

最後一句為：相容Jackson 2.9或更高版本，從Spring 5.0開始。