Support UTF-16/UTF-32 in Jackson message converter

This commit makes sure that we let Jackson deal with all the encodings
that it supports, including UTF-16 and UTF-32.

Closes gh-26627

Author: poutsma

spring-web/src/main/java/org/springframework/http/converter/json/AbstractJackson2HttpMessageConverter.java

@@ -357,7 +357,9 @@ private Object readJavaType(JavaType javaType, HttpInputMessage inputMessage) th
 		ObjectMapper objectMapper = selectObjectMapper(javaType.getRawClass(), contentType);
 		Assert.state(objectMapper != null, "No ObjectMapper for " + javaType);
 
-		boolean isUnicode = ENCODINGS.containsKey(charset.name());
+		boolean isUnicode = ENCODINGS.containsKey(charset.name()) ||
+				"UTF-16".equals(charset.name()) ||
+				"UTF-32".equals(charset.name());
 		try {
 			if (inputMessage instanceof MappingJacksonInputMessage) {
 				Class<?> deserializationView = ((MappingJacksonInputMessage) inputMessage).getDeserializationView();