Remove StringUtils from java_core.

pkg/analysis_server/lib/src/services/refactoring/extract_method.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library services.src.refactoring.extract_method;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol_server.dart' hide Element;
 import 'package:analysis_server/src/services/correction/name_suggestion.dart';
@@ skipping 31 matching lines @@
   }
   return null;
 }
 
 /**
  * Returns the "normalized" version of the given source, which is reconstructed
  * from tokens, so ignores all the comments and spaces.
  */
 String _getNormalizedSource(String src) {
   List<Token> selectionTokens = TokenUtils.getTokens(src);
-  return StringUtils.join(selectionTokens, _TOKEN_SEPARATOR);
+  return selectionTokens.join(_TOKEN_SEPARATOR);
 }
 
 /**
  * Returns the [Map] which maps [map] values to their keys.
  */
 Map<String, String> _inverseMap(Map<String, String> map) {
   Map<String, String> result = <String, String>{};
   map.forEach((String key, String value) {
     result[value] = key;
   });
@@ skipping 1179 matching lines @@
       return false;
     }
     for (int i = 0; i < parameterTypes.length; i++) {
       if (other.parameterTypes[i] != parameterTypes[i]) {
         return false;
       }
     }
     return true;
   }
 }