Delete obsolete addCharsetParameter() method

See gh-36318

spring-core/src/main/java/org/springframework/util/MimeType.java

@@ -24,7 +24,6 @@ import java.util.BitSet;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Iterator;
-import java.util.LinkedHashMap;
 import java.util.Locale;
 import java.util.Map;
 import java.util.TreeSet;
@@ -695,10 +694,4 @@ public class MimeType implements Comparable<MimeType>, Serializable {
 		return MimeTypeUtils.parseMimeType(value);
 	}
 
-	private static Map<String, String> addCharsetParameter(Charset charset, Map<String, String> parameters) {
-		Map<String, String> map = new LinkedHashMap<>(parameters);
-		map.put(PARAM_CHARSET, charset.name());
-		return map;
-	}
-
 }