Update codegen to remove analysis errors in output

Author: MichaelMarner

modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/json_serializable/api/imports.mustache

@@ -1,2 +1,3 @@
+// ignore: unused_import
 import 'dart:convert';
 import 'package:{{pubName}}/src/deserialize.dart';

modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/json_serializable/class.mustache

@@ -2,6 +2,15 @@ import 'package:json_annotation/json_annotation.dart';
 
 part '{{classFilename}}.g.dart';
 
+{{!
+    Classes with polymorphism or composition may generate unused imports,
+    these need to be ignored for said classes so that there are no lint errors.
+}}
+{{#parentModel}}
+// ignore_for_file: unused_import
+
+{{/parentModel}}
+
 @JsonSerializable(
   checked: true,
   createToJson: true,
@@ -55,7 +64,7 @@ class {{{classname}}} {
   @override
   int get hashCode =>
   {{#vars}}
-    ({{{name}}} == null ? 0 : {{{name}}}.hashCode){{^-last}} +{{/-last}}{{#-last}};{{/-last}}
+    {{#isNullable}}({{{name}}} == null ? 0 : {{{name}}}.hashCode){{/isNullable}}{{^isNullable}}{{{name}}}.hashCode{{/isNullable}}{{^-last}} +{{/-last}}{{#-last}};{{/-last}}
   {{/vars}}
 
   factory {{{classname}}}.fromJson(Map<String, dynamic> json) => _${{{classname}}}FromJson(json);

modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/json_serializable/deserialize.mustache

@@ -1,6 +1,8 @@
 {{#models}}
   {{#model}}
+  {{^isEnum}}
 import 'package:{{pubName}}/src/model/{{classFilename}}.dart';
+{{/isEnum}}
 {{/model}}
 {{/models}}
 
@@ -20,7 +22,6 @@ final _regMap = RegExp(r'^Map<String,(.*)>$');
           }
           final valueString = '$value'.toLowerCase();
           return (valueString == 'true' || valueString == '1') as ReturnType;
-          break;
         case 'double':
           return (value is double ? value : double.parse('$value')) as ReturnType;
         {{#models}}

samples/openapi3/client/petstore/dart-dio-next/petstore_client_lib_fake-json_serializable/lib/src/api/another_fake_api.dart

@@ -4,6 +4,7 @@
 
 import 'dart:async';
 
+// ignore: unused_import
 import 'dart:convert';
 import 'package:openapi/src/deserialize.dart';
 import 'package:dio/dio.dart';

samples/openapi3/client/petstore/dart-dio-next/petstore_client_lib_fake-json_serializable/lib/src/api/default_api.dart

@@ -4,6 +4,7 @@
 
 import 'dart:async';
 
+// ignore: unused_import
 import 'dart:convert';
 import 'package:openapi/src/deserialize.dart';
 import 'package:dio/dio.dart';

samples/openapi3/client/petstore/dart-dio-next/petstore_client_lib_fake-json_serializable/lib/src/api/fake_api.dart

@@ -4,6 +4,7 @@
 
 import 'dart:async';
 
+// ignore: unused_import
 import 'dart:convert';
 import 'package:openapi/src/deserialize.dart';
 import 'package:dio/dio.dart';

samples/openapi3/client/petstore/dart-dio-next/petstore_client_lib_fake-json_serializable/lib/src/api/fake_classname_tags123_api.dart

@@ -4,6 +4,7 @@
 
 import 'dart:async';
 
+// ignore: unused_import
 import 'dart:convert';
 import 'package:openapi/src/deserialize.dart';
 import 'package:dio/dio.dart';

samples/openapi3/client/petstore/dart-dio-next/petstore_client_lib_fake-json_serializable/lib/src/api/pet_api.dart

@@ -4,6 +4,7 @@
 
 import 'dart:async';
 
+// ignore: unused_import
 import 'dart:convert';
 import 'package:openapi/src/deserialize.dart';
 import 'package:dio/dio.dart';

samples/openapi3/client/petstore/dart-dio-next/petstore_client_lib_fake-json_serializable/lib/src/api/store_api.dart

@@ -4,6 +4,7 @@
 
 import 'dart:async';
 
+// ignore: unused_import
 import 'dart:convert';
 import 'package:openapi/src/deserialize.dart';
 import 'package:dio/dio.dart';

samples/openapi3/client/petstore/dart-dio-next/petstore_client_lib_fake-json_serializable/lib/src/api/user_api.dart

@@ -4,6 +4,7 @@
 
 import 'dart:async';
 
+// ignore: unused_import
 import 'dart:convert';
 import 'package:openapi/src/deserialize.dart';
 import 'package:dio/dio.dart';