Polish ObjectToStringHttpMessageConverter

Issue: SPR-9738

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

@@ -49,8 +49,6 @@ import org.springframework.util.Assert;
  */
 public class ObjectToStringHttpMessageConverter extends AbstractHttpMessageConverter<Object> {
 
-	public static final Charset DEFAULT_CHARSET = Charset.forName("ISO-8859-1");
-
 	private ConversionService conversionService;
 
 	private StringHttpMessageConverter stringHttpMessageConverter;
@@ -58,13 +56,23 @@ public class ObjectToStringHttpMessageConverter extends AbstractHttpMessageConve
 
 	/**
 	 * A constructor accepting a {@code ConversionService} to use to convert the
-	 * (String) message body to/from the target class type.
+	 * (String) message body to/from the target class type. This constructor
+	 * uses {@link StringHttpMessageConverter#DEFAULT_CHARSET} as the default
+	 * charset.
+	 *
 	 * @param conversionService the conversion service
 	 */
 	public ObjectToStringHttpMessageConverter(ConversionService conversionService) {
-		this(conversionService, DEFAULT_CHARSET);
+		this(conversionService, StringHttpMessageConverter.DEFAULT_CHARSET);
 	}
 
+	/**
+	 * A constructor accepting a {@code ConversionService} as well as a default
+	 * charset.
+	 *
+	 * @param conversionService the conversion service
+	 * @param defaultCharset the default charset
+	 */
 	public ObjectToStringHttpMessageConverter(ConversionService conversionService, Charset defaultCharset) {
 		super(new MediaType("text", "plain", defaultCharset));