Fix all strong mode warnings in protoc-plugin

lib/options.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.
 
 part of protoc;
 
 /// Helper function implementing a generic option parser that reads
 /// `request.parameters` and treats each token as either a flag ("name") or a
 /// key-value pair ("name=value"). For each option "name", it looks up whether a
 /// [SingleOptionParser] exists in [parsers] and delegates the actual parsing of
 /// the option to it. Returns `true` if no errors were reported.
-bool genericOptionsParser(
-    CodeGeneratorRequest request, CodeGeneratorResponse response,
-    Map<String, SingleOptionParser> parsers) {
+bool genericOptionsParser(CodeGeneratorRequest request,
+    CodeGeneratorResponse response, Map<String, SingleOptionParser> parsers) {
   var parameter = request.parameter != null ? request.parameter : '';
   var options = parameter.trim().split(',');
   var errors = [];
 
   for (var option in options) {
     option = option.trim();
     if (option.isEmpty) continue;
-    var reportError = (details) {
+    void reportError(String details) {
       errors.add('Error found trying to parse the option: $option.\n$details');
-    };
+    }

[Søren Gjesse, 2016/03/29 09:04:13]

???

+    ;
 
     var nameValue = option.split('=');
     if (nameValue.length != 1 && nameValue.length != 2) {
       reportError('Options should be a single token, or a name=value pair');
       continue;
     }
     var name = nameValue[0].trim();
     var parser = parsers[name];
     if (parser == null) {
       reportError('Unknown option ($name).');
@@ skipping 16 matching lines @@
   /// generate. For example `MyMessage.has_field` to `HasFld`.
   final Map<String, String> fieldNameOverrides;
 
   GenerationOptions([this.fieldNameOverrides = const {}]);
 }
 
 /// A parser for a name-value pair option. Options parsed in
 /// [genericOptionsParser] delegate to instances of this class to
 /// parse the value of a specific option.
 abstract class SingleOptionParser {
-
   /// Parse the [name]=[value] value pair and report any errors to [onError]. If
   /// the option is a flag, [value] will be null. Note, [name] is commonly
   /// unused. It is provided because [SingleOptionParser] can be registered for
   /// multiple option names in [genericOptionsParser].
   void parse(String name, String value, onError(String details));
 }
 
 /// Parser used by the compiler, which supports the `field_name` option (see
 /// [FieldNameOptionParser]) and any additional option added in [parsers]. If
 /// [parsers] has a key for `field_name`, it will be ignored.
 GenerationOptions parseGenerationOptions(
     CodeGeneratorRequest request, CodeGeneratorResponse response,
     [Map<String, SingleOptionParser> parsers]) {
   var fieldNameOptionParser = new FieldNameOptionParser();
-  var map = {};
-  if (parsers != null) parsers.forEach((k, v) { map[k] = v; });
-  map['field_name'] = fieldNameOptionParser;
-  if (genericOptionsParser(request, response, map)) {
+
+  var newParsers = <String, SingleOptionParser>{};
+  if (parsers != null) newParsers.addAll(parsers);
+  newParsers['field_name'] = fieldNameOptionParser;
+
+  if (genericOptionsParser(request, response, newParsers)) {
     return new GenerationOptions(fieldNameOptionParser.mappings);
   }
   return null;
 }
 
 /// A [SingleOptionParser] to parse the `field_name` option. This option
 /// overrides the default name given to some fields that would otherwise collide
 /// with existing field names in Dart core objects or in [GeneratedMessage].
 /// (see `README.md` for details).
 class FieldNameOptionParser implements SingleOptionParser {
@@ skipping 17 matching lines @@
     var toName = fromTo[1].trim();
     if (fromName.isEmpty || toName.isEmpty) {
       onError('Invalid field_name option, '
           '"from" and "to" names should not be empty.');
       return;
     }
 
     mappings['.$fromName'] = toName;
   }
 }