Support Encoding option when writing XML

[4n0nym1ty]

We used spring boot v3.2.1 , create bean object to convert json to xml and

jackson-dataformat-xml v2.16.1 added as dependency

@bean
public MappingJackson2XmlHttpMessageConverter converter(Jackson2ObjectMapperBuilder builder) {
XmlMapper xmlMapper = builder.createXmlMapper(true).build();
xmlMapper.configure(ToXmlGenerator.Feature.WRITE_XML_DECLARATION, true);
xmlMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
return new MappingJackson2XmlHttpMessageConverter(xmlMapper);
}

we are able to convert json to xml but we are missing encoding xml version []

[pjfanning]

duplicate of #315