diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
index 3eba155581b..23bfb825bea 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
@@ -2947,7 +2947,7 @@ public class DefaultCodegen {
             m = p.matcher(word);
         }
 
-        if (lowercaseFirstLetter) {
+        if (lowercaseFirstLetter && word.length() > 0) {
             word = word.substring(0, 1).toLowerCase() + word.substring(1);
         }
 
diff --git a/modules/swagger-codegen/src/main/resources/JavaSpring/pojo.mustache b/modules/swagger-codegen/src/main/resources/JavaSpring/pojo.mustache
index 6e5c1b74115..06c8e3048a0 100644
--- a/modules/swagger-codegen/src/main/resources/JavaSpring/pojo.mustache
+++ b/modules/swagger-codegen/src/main/resources/JavaSpring/pojo.mustache
@@ -27,7 +27,6 @@ public class {{classname}} {{#parent}}extends {{{parent}}}{{/parent}} {{#seriali
 
   {{/vars}}
   {{#vars}}
-  {{^isReadOnly}}
   public {{classname}} {{name}}({{{datatypeWithEnum}}} {{name}}) {
     this.{{name}} = {{name}};
     return this;
@@ -47,7 +46,6 @@ public class {{classname}} {{#parent}}extends {{{parent}}}{{/parent}} {{#seriali
   }
   {{/isMapContainer}}
 
-  {{/isReadOnly}}
    /**
   {{#description}}
    * {{{description}}}
@@ -70,12 +68,10 @@ public class {{classname}} {{#parent}}extends {{{parent}}}{{/parent}} {{#seriali
   public {{{datatypeWithEnum}}} {{getter}}() {
     return {{name}};
   }
-  {{^isReadOnly}}
 
   public void {{setter}}({{{datatypeWithEnum}}} {{name}}) {
     this.{{name}} = {{name}};
   }
-  {{/isReadOnly}}
 
   {{/vars}}
 
diff --git a/modules/swagger-codegen/src/main/resources/nancyfx/api.mustache b/modules/swagger-codegen/src/main/resources/nancyfx/api.mustache
index 1e66c83c769..b4213ff2056 100644
--- a/modules/swagger-codegen/src/main/resources/nancyfx/api.mustache
+++ b/modules/swagger-codegen/src/main/resources/nancyfx/api.mustache
@@ -30,7 +30,7 @@ namespace {{packageName}}.{{packageContext}}.Modules
                 {{/hasMore}}{{/isBodyParam}}{{/allParams}}{{#allParams}}{{#required}}
                 Preconditions.IsNotNull({{paramName}}, "Required parameter: '{{paramName}}' is missing at '{{operationId}}'");
                 {{/required}}{{/allParams}}
-                {{#returnType}}return {{/returnType}}service.{{operationId}}(Context{{#allParams.0}}, {{/allParams.0}}{{#allParams}}{{paramName}}{{#hasMore}}, {{/hasMore}}{{/allParams}});{{^returnType}}
+                {{#returnType}}return {{/returnType}}service.{{operationId}}(Context{{#allParams.0}}, {{/allParams.0}}{{#allParams}}{{paramName}}{{#hasMore}}, {{/hasMore}}{{/allParams}}){{#returnType}}{{#isListContainer}}.ToArray(){{/isListContainer}}{{/returnType}};{{^returnType}}
                 return new Response { ContentType = "{{produces.0.mediaType}}"};{{/returnType}}
             };
 {{/operation}}
diff --git a/modules/swagger-codegen/src/main/resources/nancyfx/parameters.mustache b/modules/swagger-codegen/src/main/resources/nancyfx/parameters.mustache
index e55a82416ec..75486f59f46 100644
--- a/modules/swagger-codegen/src/main/resources/nancyfx/parameters.mustache
+++ b/modules/swagger-codegen/src/main/resources/nancyfx/parameters.mustache
@@ -166,19 +166,19 @@ namespace {{packageName}}.{{packageContext}}.Utils
             parsers.Put(typeof(LocalTime), SafeParse(ParseLocalTime));
             parsers.Put(typeof(LocalTime?), SafeParse(ParseLocalTime));
 
-            parsers.Put(typeof(IEnumerable<string>), value => value);
-            parsers.Put(typeof(ICollection<string>), value => value);
-            parsers.Put(typeof(IList<string>), value => value);
-            parsers.Put(typeof(List<string>), value => value);
-            parsers.Put(typeof(ISet<string>), value => value);
-            parsers.Put(typeof(HashSet<string>), value => value);
+            parsers.Put(typeof(IEnumerable<string>), ImmutableListParse(value => value));
+            parsers.Put(typeof(ICollection<string>), ImmutableListParse(value => value));
+            parsers.Put(typeof(IList<string>), ImmutableListParse(value => value));
+            parsers.Put(typeof(List<string>), ListParse(value => value));
+            parsers.Put(typeof(ISet<string>), ImmutableListParse(value => value));
+            parsers.Put(typeof(HashSet<string>), SetParse(value => value));
 
-            parsers.Put(typeof(IEnumerable<bool>), ImmutableListParse(bool.Parse));
-            parsers.Put(typeof(ICollection<bool>), ImmutableListParse(bool.Parse));
-            parsers.Put(typeof(IList<bool>), ImmutableListParse(bool.Parse));
-            parsers.Put(typeof(List<bool>), ListParse(bool.Parse));
-            parsers.Put(typeof(ISet<bool>), ImmutableSetParse(bool.Parse));
-            parsers.Put(typeof(HashSet<bool>), SetParse(bool.Parse));
+            parsers.Put(typeof(IEnumerable<bool?>), NullableImmutableListParse(bool.Parse));
+            parsers.Put(typeof(ICollection<bool?>), NullableImmutableListParse(bool.Parse));
+            parsers.Put(typeof(IList<bool?>), NullableImmutableListParse(bool.Parse));
+            parsers.Put(typeof(List<bool?>), NullableListParse(bool.Parse));
+            parsers.Put(typeof(ISet<bool?>), NullableImmutableSetParse(bool.Parse));
+            parsers.Put(typeof(HashSet<bool?>), NullableSetParse(bool.Parse));
 
             parsers.Put(typeof(IEnumerable<byte>), ImmutableListParse(byte.Parse));
             parsers.Put(typeof(ICollection<byte>), ImmutableListParse(byte.Parse));
@@ -186,6 +186,7 @@ namespace {{packageName}}.{{packageContext}}.Utils
             parsers.Put(typeof(List<byte>), ListParse(byte.Parse));
             parsers.Put(typeof(ISet<byte>), ImmutableSetParse(byte.Parse));
             parsers.Put(typeof(HashSet<byte>), SetParse(byte.Parse));
+
             parsers.Put(typeof(IEnumerable<sbyte>), ImmutableListParse(sbyte.Parse));
             parsers.Put(typeof(ICollection<sbyte>), ImmutableListParse(sbyte.Parse));
             parsers.Put(typeof(IList<sbyte>), ImmutableListParse(sbyte.Parse));
@@ -199,6 +200,7 @@ namespace {{packageName}}.{{packageContext}}.Utils
             parsers.Put(typeof(List<short>), ListParse(short.Parse));
             parsers.Put(typeof(ISet<short>), ImmutableSetParse(short.Parse));
             parsers.Put(typeof(HashSet<short>), SetParse(short.Parse));
+
             parsers.Put(typeof(IEnumerable<ushort>), ImmutableListParse(ushort.Parse));
             parsers.Put(typeof(ICollection<ushort>), ImmutableListParse(ushort.Parse));
             parsers.Put(typeof(IList<ushort>), ImmutableListParse(ushort.Parse));
@@ -206,12 +208,13 @@ namespace {{packageName}}.{{packageContext}}.Utils
             parsers.Put(typeof(ISet<ushort>), ImmutableSetParse(ushort.Parse));
             parsers.Put(typeof(HashSet<ushort>), SetParse(ushort.Parse));
 
-            parsers.Put(typeof(IEnumerable<int>), ImmutableListParse(int.Parse));
-            parsers.Put(typeof(ICollection<int>), ImmutableListParse(int.Parse));
-            parsers.Put(typeof(IList<int>), ImmutableListParse(int.Parse));
-            parsers.Put(typeof(List<int>), ListParse(int.Parse));
-            parsers.Put(typeof(ISet<int>), ImmutableSetParse(int.Parse));
-            parsers.Put(typeof(HashSet<int>), SetParse(int.Parse));
+            parsers.Put(typeof(IEnumerable<int?>), NullableImmutableListParse(int.Parse));
+            parsers.Put(typeof(ICollection<int?>), NullableImmutableListParse(int.Parse));
+            parsers.Put(typeof(IList<int?>), NullableImmutableListParse(int.Parse));
+            parsers.Put(typeof(List<int?>), NullableListParse(int.Parse));
+            parsers.Put(typeof(ISet<int?>), NullableImmutableSetParse(int.Parse));
+            parsers.Put(typeof(HashSet<int?>), NullableSetParse(int.Parse));
+
             parsers.Put(typeof(IEnumerable<uint>), ImmutableListParse(uint.Parse));
             parsers.Put(typeof(ICollection<uint>), ImmutableListParse(uint.Parse));
             parsers.Put(typeof(IList<uint>), ImmutableListParse(uint.Parse));
@@ -219,12 +222,13 @@ namespace {{packageName}}.{{packageContext}}.Utils
             parsers.Put(typeof(ISet<uint>), ImmutableSetParse(uint.Parse));
             parsers.Put(typeof(HashSet<uint>), SetParse(uint.Parse));
 
-            parsers.Put(typeof(IEnumerable<long>), ImmutableListParse(long.Parse));
-            parsers.Put(typeof(ICollection<long>), ImmutableListParse(long.Parse));
-            parsers.Put(typeof(IList<long>), ImmutableListParse(long.Parse));
-            parsers.Put(typeof(List<long>), ListParse(long.Parse));
-            parsers.Put(typeof(ISet<long>), ImmutableSetParse(long.Parse));
-            parsers.Put(typeof(HashSet<long>), SetParse(long.Parse));
+            parsers.Put(typeof(IEnumerable<long?>), NullableImmutableListParse(long.Parse));
+            parsers.Put(typeof(ICollection<long?>), NullableImmutableListParse(long.Parse));
+            parsers.Put(typeof(IList<long?>), NullableImmutableListParse(long.Parse));
+            parsers.Put(typeof(List<long?>), NullableListParse(long.Parse));
+            parsers.Put(typeof(ISet<long?>), NullableImmutableSetParse(long.Parse));
+            parsers.Put(typeof(HashSet<long?>), NullableSetParse(long.Parse));
+
             parsers.Put(typeof(IEnumerable<ulong>), ImmutableListParse(ulong.Parse));
             parsers.Put(typeof(ICollection<ulong>), ImmutableListParse(ulong.Parse));
             parsers.Put(typeof(IList<ulong>), ImmutableListParse(ulong.Parse));
@@ -232,34 +236,33 @@ namespace {{packageName}}.{{packageContext}}.Utils
             parsers.Put(typeof(ISet<ulong>), ImmutableSetParse(ulong.Parse));
             parsers.Put(typeof(HashSet<ulong>), SetParse(ulong.Parse));
 
-            parsers.Put(typeof(IEnumerable<float>), ImmutableListParse(float.Parse));
-            parsers.Put(typeof(ICollection<float>), ImmutableListParse(float.Parse));
-            parsers.Put(typeof(IList<float>), ImmutableListParse(float.Parse));
-            parsers.Put(typeof(List<float>), ListParse(float.Parse));
-            parsers.Put(typeof(ISet<float>), ImmutableSetParse(float.Parse));
-            parsers.Put(typeof(HashSet<float>), SetParse(float.Parse));
+            parsers.Put(typeof(IEnumerable<float?>), NullableImmutableListParse(float.Parse));
+            parsers.Put(typeof(ICollection<float?>), NullableImmutableListParse(float.Parse));
+            parsers.Put(typeof(IList<float?>), NullableImmutableListParse(float.Parse));
+            parsers.Put(typeof(List<float?>), NullableListParse(float.Parse));
+            parsers.Put(typeof(ISet<float?>), NullableImmutableSetParse(float.Parse));
+            parsers.Put(typeof(HashSet<float?>), NullableSetParse(float.Parse));
 
-            parsers.Put(typeof(IEnumerable<double>), ImmutableListParse(double.Parse));
-            parsers.Put(typeof(ICollection<double>), ImmutableListParse(double.Parse));
-            parsers.Put(typeof(IList<double>), ImmutableListParse(double.Parse));
-            parsers.Put(typeof(List<double>), ListParse(double.Parse));
-            parsers.Put(typeof(ISet<double>), ImmutableSetParse(double.Parse));
-            parsers.Put(typeof(HashSet<double>), SetParse(double.Parse));
+            parsers.Put(typeof(IEnumerable<double?>), NullableImmutableListParse(double.Parse));
+            parsers.Put(typeof(ICollection<double?>), NullableImmutableListParse(double.Parse));
+            parsers.Put(typeof(IList<double?>), NullableImmutableListParse(double.Parse));
+            parsers.Put(typeof(List<double?>), NullableListParse(double.Parse));
+            parsers.Put(typeof(ISet<double?>), NullableImmutableSetParse(double.Parse));
+            parsers.Put(typeof(HashSet<double?>), NullableSetParse(double.Parse));
 
-            parsers.Put(typeof(IEnumerable<decimal>), ImmutableListParse(decimal.Parse));
-            parsers.Put(typeof(ICollection<decimal>), ImmutableListParse(decimal.Parse));
-            parsers.Put(typeof(IList<decimal>), ImmutableListParse(decimal.Parse));
-            parsers.Put(typeof(List<decimal>), ListParse(decimal.Parse));
-            parsers.Put(typeof(ISet<decimal>), ImmutableSetParse(decimal.Parse));
-            parsers.Put(typeof(HashSet<decimal>), SetParse(decimal.Parse));
+            parsers.Put(typeof(IEnumerable<decimal?>), NullableImmutableListParse(decimal.Parse));
+            parsers.Put(typeof(ICollection<decimal?>), NullableImmutableListParse(decimal.Parse));
+            parsers.Put(typeof(IList<decimal?>), NullableImmutableListParse(decimal.Parse));
+            parsers.Put(typeof(List<decimal?>), NullableListParse(decimal.Parse));
+            parsers.Put(typeof(ISet<decimal?>), NullableImmutableSetParse(decimal.Parse));
+            parsers.Put(typeof(HashSet<decimal?>), NullableSetParse(decimal.Parse));
 
-
-            parsers.Put(typeof(IEnumerable<DateTime>), ImmutableListParse(DateTime.Parse));
-            parsers.Put(typeof(ICollection<DateTime>), ImmutableListParse(DateTime.Parse));
-            parsers.Put(typeof(IList<DateTime>), ImmutableListParse(DateTime.Parse));
-            parsers.Put(typeof(List<DateTime>), ListParse(DateTime.Parse));
-            parsers.Put(typeof(ISet<DateTime>), ImmutableSetParse(DateTime.Parse));
-            parsers.Put(typeof(HashSet<DateTime>), SetParse(DateTime.Parse));
+            parsers.Put(typeof(IEnumerable<DateTime?>), NullableImmutableListParse(DateTime.Parse));
+            parsers.Put(typeof(ICollection<DateTime?>), NullableImmutableListParse(DateTime.Parse));
+            parsers.Put(typeof(IList<DateTime?>), NullableImmutableListParse(DateTime.Parse));
+            parsers.Put(typeof(List<DateTime?>), NullableListParse(DateTime.Parse));
+            parsers.Put(typeof(ISet<DateTime?>), NullableImmutableSetParse(DateTime.Parse));
+            parsers.Put(typeof(HashSet<DateTime?>), NullableSetParse(DateTime.Parse));
 
             parsers.Put(typeof(IEnumerable<TimeSpan>), ImmutableListParse(TimeSpan.Parse));
             parsers.Put(typeof(ICollection<TimeSpan>), ImmutableListParse(TimeSpan.Parse));
@@ -295,6 +298,11 @@ namespace {{packageName}}.{{packageContext}}.Utils
             };
         }
 
+        private static Func<Parameter, object> NullableListParse<T>(Func<string, T> itemParser) where T: struct
+        {
+            return ListParse(it => it.ToNullable(itemParser));
+        }
+
         private static Func<Parameter, object> ListParse<T>(Func<string, T> itemParser)
         {
             return parameter =>
@@ -303,15 +311,15 @@ namespace {{packageName}}.{{packageContext}}.Utils
                 {
                     return new List<T>();
                 }
-                var results = parameter.Value.Split(new[] { ',' }, StringSplitOptions.None)
-                    .Where(it => it != null)
-                    .Select(it => it.Trim())
-                    .Select(itemParser)
-                    .ToList();
-                return results;
+                return ParseCollection(parameter.Value, itemParser).ToList();
             };
         }
 
+        private static Func<Parameter, object> NullableImmutableListParse<T>(Func<string, T> itemParser) where T: struct
+        {
+            return ImmutableListParse(it => it.ToNullable(itemParser));
+        }
+
         private static Func<Parameter, object> ImmutableListParse<T>(Func<string, T> itemParser)
         {
             return parameter =>
@@ -320,15 +328,15 @@ namespace {{packageName}}.{{packageContext}}.Utils
                 {
                     return Lists.EmptyList<T>();
                 }
-                var results = parameter.Value.Split(new[] { ',' }, StringSplitOptions.None)
-                    .Where(it => it != null)
-                    .Select(it => it.Trim())
-                    .Select(itemParser)
-                    .ToImmutableList();
-                return results;
+                return ParseCollection(parameter.Value, itemParser).ToImmutableList();
             };
         }
 
+        private static Func<Parameter, object> NullableSetParse<T>(Func<string, T> itemParser) where T: struct
+        {
+            return SetParse(it => it.ToNullable(itemParser));
+        }
+
         private static Func<Parameter, object> SetParse<T>(Func<string, T> itemParser)
         {
             return parameter =>
@@ -337,15 +345,15 @@ namespace {{packageName}}.{{packageContext}}.Utils
                 {
                     return new HashSet<T>();
                 }
-                var results = parameter.Value.Split(new[] { ',' }, StringSplitOptions.None)
-                    .Where(it => it != null)
-                    .Select(it => it.Trim())
-                    .Select(itemParser)
-                    .ToSet();
-                return results;
+                return ParseCollection(parameter.Value, itemParser).ToSet();
             };
         }
 
+        private static Func<Parameter, object> NullableImmutableSetParse<T>(Func<string, T> itemParser) where T: struct
+        {
+            return ImmutableSetParse(it => it.ToNullable(itemParser));
+        }
+
         private static Func<Parameter, object> ImmutableSetParse<T>(Func<string, T> itemParser)
         {
             return parameter =>
@@ -354,12 +362,7 @@ namespace {{packageName}}.{{packageContext}}.Utils
                 {
                     return Sets.EmptySet<T>();
                 }
-                var results = parameter.Value.Split(new[] { ',' }, StringSplitOptions.None)
-                    .Where(it => it != null)
-                    .Select(it => it.Trim())
-                    .Select(itemParser)
-                    .ToImmutableHashSet();
-                return results;
+                return ParseCollection(parameter.Value, itemParser).ToImmutableHashSet();
             };
         }
 
@@ -386,6 +389,32 @@ namespace {{packageName}}.{{packageContext}}.Utils
                 parameter.Name, parameter.Value, type));
         }
 
+        private static IEnumerable<T> ParseCollection<T>(string value, Func<string, T> itemParser)
+        {
+            var results = value.Split(new[] { ',' }, StringSplitOptions.None)
+                        .Where(it => it != null)
+                        .Select(it => it.Trim())
+                        .Select(itemParser);
+            return results;
+        }
+
+        public static T? ToNullable<T>(this string s, Func<string, T> itemParser) where T : struct
+        {
+            T? result = new T?();
+            try
+            {
+                if (!string.IsNullOrEmpty(s) && s.Trim().Length > 0)
+                {
+                    result = itemParser(s);
+                }
+            }
+            catch (Exception e)
+            {
+                throw new InvalidOperationException(Strings.Format("Unable to parse value: '{0}' to nullable: '{1}'", s, typeof(T).ToString()), e);
+            }
+            return result;
+        }
+
         private class Parameter
         {
             internal string Name { get; private set; }
diff --git a/modules/swagger-codegen/src/main/resources/ruby/api.mustache b/modules/swagger-codegen/src/main/resources/ruby/api.mustache
index 7071e72e849..8366246f467 100644
--- a/modules/swagger-codegen/src/main/resources/ruby/api.mustache
+++ b/modules/swagger-codegen/src/main/resources/ruby/api.mustache
@@ -50,9 +50,16 @@ module {{moduleName}}
       {{/required}}
       {{^required}}
       {{#isEnum}}
+      {{#collectionFormat}}
+      if opts[:'{{{paramName}}}'] && !opts[:'{{{paramName}}}'].all?{|item| [{{#allowableValues}}{{#values}}'{{{this}}}'{{^-last}}, {{/-last}}{{/values}}{{/allowableValues}}].include?(item)}
+        fail ArgumentError, 'invalid value for "{{{paramName}}}", must include one of {{#allowableValues}}{{#values}}{{{this}}}{{^-last}}, {{/-last}}{{/values}}{{/allowableValues}}'
+      end
+      {{/collectionFormat}}
+      {{^collectionFormat}}
       if opts[:'{{{paramName}}}'] && ![{{#allowableValues}}{{#values}}'{{{this}}}'{{^-last}}, {{/-last}}{{/values}}{{/allowableValues}}].include?(opts[:'{{{paramName}}}'])
         fail ArgumentError, 'invalid value for "{{{paramName}}}", must be one of {{#allowableValues}}{{#values}}{{{this}}}{{^-last}}, {{/-last}}{{/values}}{{/allowableValues}}'
       end
+      {{/collectionFormat}}
       {{/isEnum}}
       {{/required}}
       {{#hasValidation}}
diff --git a/pom.xml b/pom.xml
index 894931d4e80..b5310be9090 100644
--- a/pom.xml
+++ b/pom.xml
@@ -807,7 +807,7 @@
         </repository>
     </repositories>
     <properties>
-        <swagger-parser-version>1.0.23</swagger-parser-version>
+        <swagger-parser-version>1.0.24-SNAPSHOT</swagger-parser-version>
         <scala-version>2.11.1</scala-version>
         <felix-version>2.3.4</felix-version>
         <swagger-core-version>1.5.10</swagger-core-version>
diff --git a/samples/client/petstore/ruby/lib/petstore/api/fake_api.rb b/samples/client/petstore/ruby/lib/petstore/api/fake_api.rb
index 0eaba370798..3500dfbb52f 100644
--- a/samples/client/petstore/ruby/lib/petstore/api/fake_api.rb
+++ b/samples/client/petstore/ruby/lib/petstore/api/fake_api.rb
@@ -275,20 +275,20 @@ module Petstore
       if @api_client.config.debugging
         @api_client.config.logger.debug "Calling API: FakeApi.test_enum_parameters ..."
       end
-      if opts[:'enum_form_string_array'] && !['>', '$'].include?(opts[:'enum_form_string_array'])
-        fail ArgumentError, 'invalid value for "enum_form_string_array", must be one of >, $'
+      if opts[:'enum_form_string_array'] && !opts[:'enum_form_string_array'].all?{|item| ['>', '$'].include?(item)}
+        fail ArgumentError, 'invalid value for "enum_form_string_array", must include one of >, $'
       end
       if opts[:'enum_form_string'] && !['_abc', '-efg', '(xyz)'].include?(opts[:'enum_form_string'])
         fail ArgumentError, 'invalid value for "enum_form_string", must be one of _abc, -efg, (xyz)'
       end
-      if opts[:'enum_header_string_array'] && !['>', '$'].include?(opts[:'enum_header_string_array'])
-        fail ArgumentError, 'invalid value for "enum_header_string_array", must be one of >, $'
+      if opts[:'enum_header_string_array'] && !opts[:'enum_header_string_array'].all?{|item| ['>', '$'].include?(item)}
+        fail ArgumentError, 'invalid value for "enum_header_string_array", must include one of >, $'
       end
       if opts[:'enum_header_string'] && !['_abc', '-efg', '(xyz)'].include?(opts[:'enum_header_string'])
         fail ArgumentError, 'invalid value for "enum_header_string", must be one of _abc, -efg, (xyz)'
       end
-      if opts[:'enum_query_string_array'] && !['>', '$'].include?(opts[:'enum_query_string_array'])
-        fail ArgumentError, 'invalid value for "enum_query_string_array", must be one of >, $'
+      if opts[:'enum_query_string_array'] && !opts[:'enum_query_string_array'].all?{|item| ['>', '$'].include?(item)}
+        fail ArgumentError, 'invalid value for "enum_query_string_array", must include one of >, $'
       end
       if opts[:'enum_query_string'] && !['_abc', '-efg', '(xyz)'].include?(opts[:'enum_query_string'])
         fail ArgumentError, 'invalid value for "enum_query_string", must be one of _abc, -efg, (xyz)'
diff --git a/samples/client/petstore/spring-cloud/src/main/java/io/swagger/api/PetApi.java b/samples/client/petstore/spring-cloud/src/main/java/io/swagger/api/PetApi.java
index 812ca04e270..dbdffde69ce 100644
--- a/samples/client/petstore/spring-cloud/src/main/java/io/swagger/api/PetApi.java
+++ b/samples/client/petstore/spring-cloud/src/main/java/io/swagger/api/PetApi.java
@@ -1,8 +1,8 @@
 package io.swagger.api;
 
 import io.swagger.model.Pet;
-import io.swagger.model.ModelApiResponse;
 import java.io.File;
+import io.swagger.model.ModelApiResponse;
 
 import io.swagger.annotations.*;
 import org.springframework.http.ResponseEntity;
diff --git a/samples/client/petstore/spring-stubs/src/main/java/io/swagger/api/PetApi.java b/samples/client/petstore/spring-stubs/src/main/java/io/swagger/api/PetApi.java
index 04c4ed27aa3..abe1992830a 100644
--- a/samples/client/petstore/spring-stubs/src/main/java/io/swagger/api/PetApi.java
+++ b/samples/client/petstore/spring-stubs/src/main/java/io/swagger/api/PetApi.java
@@ -1,8 +1,8 @@
 package io.swagger.api;
 
 import io.swagger.model.Pet;
-import io.swagger.model.ModelApiResponse;
 import java.io.File;
+import io.swagger.model.ModelApiResponse;
 
 import io.swagger.annotations.*;
 import org.springframework.http.ResponseEntity;
diff --git a/samples/server/petstore/nancyfx/IO.Swagger.sln b/samples/server/petstore/nancyfx/IO.Swagger.sln
index e6fd22af6f6..09301395de7 100644
--- a/samples/server/petstore/nancyfx/IO.Swagger.sln
+++ b/samples/server/petstore/nancyfx/IO.Swagger.sln
@@ -2,7 +2,7 @@ Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio 2012
 VisualStudioVersion = 12.0.0.0
 MinimumVisualStudioVersion = 10.0.0.1
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "IO.Swagger", "src\IO.Swagger\IO.Swagger.csproj", "{7D50D142-14E1-4E99-842B-18D3AF159948}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "IO.Swagger", "src\IO.Swagger\IO.Swagger.csproj", "{3B55ED13-A471-44B1-A8D5-C158723C0A0C}"
 EndProject
 Global
 GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -10,17 +10,10 @@ Debug|Any CPU = Debug|Any CPU
 Release|Any CPU = Release|Any CPU
 EndGlobalSection
 GlobalSection(ProjectConfigurationPlatforms) = postSolution
-<<<<<<< HEAD
-{7D50D142-14E1-4E99-842B-18D3AF159948}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-{7D50D142-14E1-4E99-842B-18D3AF159948}.Debug|Any CPU.Build.0 = Debug|Any CPU
-{7D50D142-14E1-4E99-842B-18D3AF159948}.Release|Any CPU.ActiveCfg = Release|Any CPU
-{7D50D142-14E1-4E99-842B-18D3AF159948}.Release|Any CPU.Build.0 = Release|Any CPU
-=======
-{1CE943E7-586D-4D9C-BE8B-3E005FDC39D1}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-{1CE943E7-586D-4D9C-BE8B-3E005FDC39D1}.Debug|Any CPU.Build.0 = Debug|Any CPU
-{1CE943E7-586D-4D9C-BE8B-3E005FDC39D1}.Release|Any CPU.ActiveCfg = Release|Any CPU
-{1CE943E7-586D-4D9C-BE8B-3E005FDC39D1}.Release|Any CPU.Build.0 = Release|Any CPU
->>>>>>> 92c474b2c235f4635e4be43a97c7941fec64dc82
+{3B55ED13-A471-44B1-A8D5-C158723C0A0C}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+{3B55ED13-A471-44B1-A8D5-C158723C0A0C}.Debug|Any CPU.Build.0 = Debug|Any CPU
+{3B55ED13-A471-44B1-A8D5-C158723C0A0C}.Release|Any CPU.ActiveCfg = Release|Any CPU
+{3B55ED13-A471-44B1-A8D5-C158723C0A0C}.Release|Any CPU.Build.0 = Release|Any CPU
 {19F1DEBC-DE5E-4517-8062-F000CD499087}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 {19F1DEBC-DE5E-4517-8062-F000CD499087}.Debug|Any CPU.Build.0 = Debug|Any CPU
 {19F1DEBC-DE5E-4517-8062-F000CD499087}.Release|Any CPU.ActiveCfg = Release|Any CPU
@@ -29,4 +22,4 @@ EndGlobalSection
 GlobalSection(SolutionProperties) = preSolution
 HideSolutionNode = FALSE
 EndGlobalSection
-EndGlobal
+EndGlobal
\ No newline at end of file
diff --git a/samples/server/petstore/nancyfx/src/IO.Swagger/IO.Swagger.csproj b/samples/server/petstore/nancyfx/src/IO.Swagger/IO.Swagger.csproj
index 60535f7aae6..a103786b912 100644
--- a/samples/server/petstore/nancyfx/src/IO.Swagger/IO.Swagger.csproj
+++ b/samples/server/petstore/nancyfx/src/IO.Swagger/IO.Swagger.csproj
@@ -3,7 +3,7 @@
     <PropertyGroup>
         <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
         <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
-        <ProjectGuid>{7D50D142-14E1-4E99-842B-18D3AF159948}</ProjectGuid>
+        <ProjectGuid>{3B55ED13-A471-44B1-A8D5-C158723C0A0C}</ProjectGuid>
         <OutputType>Library</OutputType>
         <AppDesignerFolder>Properties</AppDesignerFolder>
         <RootNamespace>IO.Swagger.v2</RootNamespace>
@@ -63,3 +63,4 @@
     </ItemGroup>
     <Import Project="$(MsBuildToolsPath)\Microsoft.CSharp.targets"/>
 </Project>
+
diff --git a/samples/server/petstore/nancyfx/src/IO.Swagger/Modules/PetModule.cs b/samples/server/petstore/nancyfx/src/IO.Swagger/Modules/PetModule.cs
index d6922531e24..edfa0ecac4a 100644
--- a/samples/server/petstore/nancyfx/src/IO.Swagger/Modules/PetModule.cs
+++ b/samples/server/petstore/nancyfx/src/IO.Swagger/Modules/PetModule.cs
@@ -55,7 +55,7 @@ namespace IO.Swagger.v2.Modules
                 var status = Parameters.ValueOf<FindPetsByStatusStatusEnum?>(parameters, Context.Request, "status", ParameterType.Query);
                 Preconditions.IsNotNull(status, "Required parameter: 'status' is missing at 'FindPetsByStatus'");
                 
-                return service.FindPetsByStatus(Context, status);
+                return service.FindPetsByStatus(Context, status).ToArray();
             };
 
             Get["/pet/findByTags"] = parameters =>
@@ -63,7 +63,7 @@ namespace IO.Swagger.v2.Modules
                 var tags = Parameters.ValueOf<List<string>>(parameters, Context.Request, "tags", ParameterType.Query);
                 Preconditions.IsNotNull(tags, "Required parameter: 'tags' is missing at 'FindPetsByTags'");
                 
-                return service.FindPetsByTags(Context, tags);
+                return service.FindPetsByTags(Context, tags).ToArray();
             };
 
             Get["/pet/{petId}"] = parameters =>
diff --git a/samples/server/petstore/nancyfx/src/IO.Swagger/Utils/Parameters.cs b/samples/server/petstore/nancyfx/src/IO.Swagger/Utils/Parameters.cs
index 7f0e848f98a..6175758fd9a 100644
--- a/samples/server/petstore/nancyfx/src/IO.Swagger/Utils/Parameters.cs
+++ b/samples/server/petstore/nancyfx/src/IO.Swagger/Utils/Parameters.cs
@@ -166,19 +166,19 @@ namespace IO.Swagger.v2.Utils
             parsers.Put(typeof(LocalTime), SafeParse(ParseLocalTime));
             parsers.Put(typeof(LocalTime?), SafeParse(ParseLocalTime));
 
-            parsers.Put(typeof(IEnumerable<string>), value => value);
-            parsers.Put(typeof(ICollection<string>), value => value);
-            parsers.Put(typeof(IList<string>), value => value);
-            parsers.Put(typeof(List<string>), value => value);
-            parsers.Put(typeof(ISet<string>), value => value);
-            parsers.Put(typeof(HashSet<string>), value => value);
+            parsers.Put(typeof(IEnumerable<string>), ImmutableListParse(value => value));
+            parsers.Put(typeof(ICollection<string>), ImmutableListParse(value => value));
+            parsers.Put(typeof(IList<string>), ImmutableListParse(value => value));
+            parsers.Put(typeof(List<string>), ListParse(value => value));
+            parsers.Put(typeof(ISet<string>), ImmutableListParse(value => value));
+            parsers.Put(typeof(HashSet<string>), SetParse(value => value));
 
-            parsers.Put(typeof(IEnumerable<bool>), ImmutableListParse(bool.Parse));
-            parsers.Put(typeof(ICollection<bool>), ImmutableListParse(bool.Parse));
-            parsers.Put(typeof(IList<bool>), ImmutableListParse(bool.Parse));
-            parsers.Put(typeof(List<bool>), ListParse(bool.Parse));
-            parsers.Put(typeof(ISet<bool>), ImmutableSetParse(bool.Parse));
-            parsers.Put(typeof(HashSet<bool>), SetParse(bool.Parse));
+            parsers.Put(typeof(IEnumerable<bool?>), NullableImmutableListParse(bool.Parse));
+            parsers.Put(typeof(ICollection<bool?>), NullableImmutableListParse(bool.Parse));
+            parsers.Put(typeof(IList<bool?>), NullableImmutableListParse(bool.Parse));
+            parsers.Put(typeof(List<bool?>), NullableListParse(bool.Parse));
+            parsers.Put(typeof(ISet<bool?>), NullableImmutableSetParse(bool.Parse));
+            parsers.Put(typeof(HashSet<bool?>), NullableSetParse(bool.Parse));
 
             parsers.Put(typeof(IEnumerable<byte>), ImmutableListParse(byte.Parse));
             parsers.Put(typeof(ICollection<byte>), ImmutableListParse(byte.Parse));
@@ -186,6 +186,7 @@ namespace IO.Swagger.v2.Utils
             parsers.Put(typeof(List<byte>), ListParse(byte.Parse));
             parsers.Put(typeof(ISet<byte>), ImmutableSetParse(byte.Parse));
             parsers.Put(typeof(HashSet<byte>), SetParse(byte.Parse));
+
             parsers.Put(typeof(IEnumerable<sbyte>), ImmutableListParse(sbyte.Parse));
             parsers.Put(typeof(ICollection<sbyte>), ImmutableListParse(sbyte.Parse));
             parsers.Put(typeof(IList<sbyte>), ImmutableListParse(sbyte.Parse));
@@ -199,6 +200,7 @@ namespace IO.Swagger.v2.Utils
             parsers.Put(typeof(List<short>), ListParse(short.Parse));
             parsers.Put(typeof(ISet<short>), ImmutableSetParse(short.Parse));
             parsers.Put(typeof(HashSet<short>), SetParse(short.Parse));
+
             parsers.Put(typeof(IEnumerable<ushort>), ImmutableListParse(ushort.Parse));
             parsers.Put(typeof(ICollection<ushort>), ImmutableListParse(ushort.Parse));
             parsers.Put(typeof(IList<ushort>), ImmutableListParse(ushort.Parse));
@@ -206,12 +208,13 @@ namespace IO.Swagger.v2.Utils
             parsers.Put(typeof(ISet<ushort>), ImmutableSetParse(ushort.Parse));
             parsers.Put(typeof(HashSet<ushort>), SetParse(ushort.Parse));
 
-            parsers.Put(typeof(IEnumerable<int>), ImmutableListParse(int.Parse));
-            parsers.Put(typeof(ICollection<int>), ImmutableListParse(int.Parse));
-            parsers.Put(typeof(IList<int>), ImmutableListParse(int.Parse));
-            parsers.Put(typeof(List<int>), ListParse(int.Parse));
-            parsers.Put(typeof(ISet<int>), ImmutableSetParse(int.Parse));
-            parsers.Put(typeof(HashSet<int>), SetParse(int.Parse));
+            parsers.Put(typeof(IEnumerable<int?>), NullableImmutableListParse(int.Parse));
+            parsers.Put(typeof(ICollection<int?>), NullableImmutableListParse(int.Parse));
+            parsers.Put(typeof(IList<int?>), NullableImmutableListParse(int.Parse));
+            parsers.Put(typeof(List<int?>), NullableListParse(int.Parse));
+            parsers.Put(typeof(ISet<int?>), NullableImmutableSetParse(int.Parse));
+            parsers.Put(typeof(HashSet<int?>), NullableSetParse(int.Parse));
+
             parsers.Put(typeof(IEnumerable<uint>), ImmutableListParse(uint.Parse));
             parsers.Put(typeof(ICollection<uint>), ImmutableListParse(uint.Parse));
             parsers.Put(typeof(IList<uint>), ImmutableListParse(uint.Parse));
@@ -219,12 +222,13 @@ namespace IO.Swagger.v2.Utils
             parsers.Put(typeof(ISet<uint>), ImmutableSetParse(uint.Parse));
             parsers.Put(typeof(HashSet<uint>), SetParse(uint.Parse));
 
-            parsers.Put(typeof(IEnumerable<long>), ImmutableListParse(long.Parse));
-            parsers.Put(typeof(ICollection<long>), ImmutableListParse(long.Parse));
-            parsers.Put(typeof(IList<long>), ImmutableListParse(long.Parse));
-            parsers.Put(typeof(List<long>), ListParse(long.Parse));
-            parsers.Put(typeof(ISet<long>), ImmutableSetParse(long.Parse));
-            parsers.Put(typeof(HashSet<long>), SetParse(long.Parse));
+            parsers.Put(typeof(IEnumerable<long?>), NullableImmutableListParse(long.Parse));
+            parsers.Put(typeof(ICollection<long?>), NullableImmutableListParse(long.Parse));
+            parsers.Put(typeof(IList<long?>), NullableImmutableListParse(long.Parse));
+            parsers.Put(typeof(List<long?>), NullableListParse(long.Parse));
+            parsers.Put(typeof(ISet<long?>), NullableImmutableSetParse(long.Parse));
+            parsers.Put(typeof(HashSet<long?>), NullableSetParse(long.Parse));
+
             parsers.Put(typeof(IEnumerable<ulong>), ImmutableListParse(ulong.Parse));
             parsers.Put(typeof(ICollection<ulong>), ImmutableListParse(ulong.Parse));
             parsers.Put(typeof(IList<ulong>), ImmutableListParse(ulong.Parse));
@@ -232,34 +236,33 @@ namespace IO.Swagger.v2.Utils
             parsers.Put(typeof(ISet<ulong>), ImmutableSetParse(ulong.Parse));
             parsers.Put(typeof(HashSet<ulong>), SetParse(ulong.Parse));
 
-            parsers.Put(typeof(IEnumerable<float>), ImmutableListParse(float.Parse));
-            parsers.Put(typeof(ICollection<float>), ImmutableListParse(float.Parse));
-            parsers.Put(typeof(IList<float>), ImmutableListParse(float.Parse));
-            parsers.Put(typeof(List<float>), ListParse(float.Parse));
-            parsers.Put(typeof(ISet<float>), ImmutableSetParse(float.Parse));
-            parsers.Put(typeof(HashSet<float>), SetParse(float.Parse));
+            parsers.Put(typeof(IEnumerable<float?>), NullableImmutableListParse(float.Parse));
+            parsers.Put(typeof(ICollection<float?>), NullableImmutableListParse(float.Parse));
+            parsers.Put(typeof(IList<float?>), NullableImmutableListParse(float.Parse));
+            parsers.Put(typeof(List<float?>), NullableListParse(float.Parse));
+            parsers.Put(typeof(ISet<float?>), NullableImmutableSetParse(float.Parse));
+            parsers.Put(typeof(HashSet<float?>), NullableSetParse(float.Parse));
 
-            parsers.Put(typeof(IEnumerable<double>), ImmutableListParse(double.Parse));
-            parsers.Put(typeof(ICollection<double>), ImmutableListParse(double.Parse));
-            parsers.Put(typeof(IList<double>), ImmutableListParse(double.Parse));
-            parsers.Put(typeof(List<double>), ListParse(double.Parse));
-            parsers.Put(typeof(ISet<double>), ImmutableSetParse(double.Parse));
-            parsers.Put(typeof(HashSet<double>), SetParse(double.Parse));
+            parsers.Put(typeof(IEnumerable<double?>), NullableImmutableListParse(double.Parse));
+            parsers.Put(typeof(ICollection<double?>), NullableImmutableListParse(double.Parse));
+            parsers.Put(typeof(IList<double?>), NullableImmutableListParse(double.Parse));
+            parsers.Put(typeof(List<double?>), NullableListParse(double.Parse));
+            parsers.Put(typeof(ISet<double?>), NullableImmutableSetParse(double.Parse));
+            parsers.Put(typeof(HashSet<double?>), NullableSetParse(double.Parse));
 
-            parsers.Put(typeof(IEnumerable<decimal>), ImmutableListParse(decimal.Parse));
-            parsers.Put(typeof(ICollection<decimal>), ImmutableListParse(decimal.Parse));
-            parsers.Put(typeof(IList<decimal>), ImmutableListParse(decimal.Parse));
-            parsers.Put(typeof(List<decimal>), ListParse(decimal.Parse));
-            parsers.Put(typeof(ISet<decimal>), ImmutableSetParse(decimal.Parse));
-            parsers.Put(typeof(HashSet<decimal>), SetParse(decimal.Parse));
+            parsers.Put(typeof(IEnumerable<decimal?>), NullableImmutableListParse(decimal.Parse));
+            parsers.Put(typeof(ICollection<decimal?>), NullableImmutableListParse(decimal.Parse));
+            parsers.Put(typeof(IList<decimal?>), NullableImmutableListParse(decimal.Parse));
+            parsers.Put(typeof(List<decimal?>), NullableListParse(decimal.Parse));
+            parsers.Put(typeof(ISet<decimal?>), NullableImmutableSetParse(decimal.Parse));
+            parsers.Put(typeof(HashSet<decimal?>), NullableSetParse(decimal.Parse));
 
-
-            parsers.Put(typeof(IEnumerable<DateTime>), ImmutableListParse(DateTime.Parse));
-            parsers.Put(typeof(ICollection<DateTime>), ImmutableListParse(DateTime.Parse));
-            parsers.Put(typeof(IList<DateTime>), ImmutableListParse(DateTime.Parse));
-            parsers.Put(typeof(List<DateTime>), ListParse(DateTime.Parse));
-            parsers.Put(typeof(ISet<DateTime>), ImmutableSetParse(DateTime.Parse));
-            parsers.Put(typeof(HashSet<DateTime>), SetParse(DateTime.Parse));
+            parsers.Put(typeof(IEnumerable<DateTime?>), NullableImmutableListParse(DateTime.Parse));
+            parsers.Put(typeof(ICollection<DateTime?>), NullableImmutableListParse(DateTime.Parse));
+            parsers.Put(typeof(IList<DateTime?>), NullableImmutableListParse(DateTime.Parse));
+            parsers.Put(typeof(List<DateTime?>), NullableListParse(DateTime.Parse));
+            parsers.Put(typeof(ISet<DateTime?>), NullableImmutableSetParse(DateTime.Parse));
+            parsers.Put(typeof(HashSet<DateTime?>), NullableSetParse(DateTime.Parse));
 
             parsers.Put(typeof(IEnumerable<TimeSpan>), ImmutableListParse(TimeSpan.Parse));
             parsers.Put(typeof(ICollection<TimeSpan>), ImmutableListParse(TimeSpan.Parse));
@@ -295,6 +298,11 @@ namespace IO.Swagger.v2.Utils
             };
         }
 
+        private static Func<Parameter, object> NullableListParse<T>(Func<string, T> itemParser) where T: struct
+        {
+            return ListParse(it => it.ToNullable(itemParser));
+        }
+
         private static Func<Parameter, object> ListParse<T>(Func<string, T> itemParser)
         {
             return parameter =>
@@ -303,15 +311,15 @@ namespace IO.Swagger.v2.Utils
                 {
                     return new List<T>();
                 }
-                var results = parameter.Value.Split(new[] { ',' }, StringSplitOptions.None)
-                    .Where(it => it != null)
-                    .Select(it => it.Trim())
-                    .Select(itemParser)
-                    .ToList();
-                return results;
+                return ParseCollection(parameter.Value, itemParser).ToList();
             };
         }
 
+        private static Func<Parameter, object> NullableImmutableListParse<T>(Func<string, T> itemParser) where T: struct
+        {
+            return ImmutableListParse(it => it.ToNullable(itemParser));
+        }
+
         private static Func<Parameter, object> ImmutableListParse<T>(Func<string, T> itemParser)
         {
             return parameter =>
@@ -320,15 +328,15 @@ namespace IO.Swagger.v2.Utils
                 {
                     return Lists.EmptyList<T>();
                 }
-                var results = parameter.Value.Split(new[] { ',' }, StringSplitOptions.None)
-                    .Where(it => it != null)
-                    .Select(it => it.Trim())
-                    .Select(itemParser)
-                    .ToImmutableList();
-                return results;
+                return ParseCollection(parameter.Value, itemParser).ToImmutableList();
             };
         }
 
+        private static Func<Parameter, object> NullableSetParse<T>(Func<string, T> itemParser) where T: struct
+        {
+            return SetParse(it => it.ToNullable(itemParser));
+        }
+
         private static Func<Parameter, object> SetParse<T>(Func<string, T> itemParser)
         {
             return parameter =>
@@ -337,15 +345,15 @@ namespace IO.Swagger.v2.Utils
                 {
                     return new HashSet<T>();
                 }
-                var results = parameter.Value.Split(new[] { ',' }, StringSplitOptions.None)
-                    .Where(it => it != null)
-                    .Select(it => it.Trim())
-                    .Select(itemParser)
-                    .ToSet();
-                return results;
+                return ParseCollection(parameter.Value, itemParser).ToSet();
             };
         }
 
+        private static Func<Parameter, object> NullableImmutableSetParse<T>(Func<string, T> itemParser) where T: struct
+        {
+            return ImmutableSetParse(it => it.ToNullable(itemParser));
+        }
+
         private static Func<Parameter, object> ImmutableSetParse<T>(Func<string, T> itemParser)
         {
             return parameter =>
@@ -354,12 +362,7 @@ namespace IO.Swagger.v2.Utils
                 {
                     return Sets.EmptySet<T>();
                 }
-                var results = parameter.Value.Split(new[] { ',' }, StringSplitOptions.None)
-                    .Where(it => it != null)
-                    .Select(it => it.Trim())
-                    .Select(itemParser)
-                    .ToImmutableHashSet();
-                return results;
+                return ParseCollection(parameter.Value, itemParser).ToImmutableHashSet();
             };
         }
 
@@ -386,6 +389,32 @@ namespace IO.Swagger.v2.Utils
                 parameter.Name, parameter.Value, type));
         }
 
+        private static IEnumerable<T> ParseCollection<T>(string value, Func<string, T> itemParser)
+        {
+            var results = value.Split(new[] { ',' }, StringSplitOptions.None)
+                        .Where(it => it != null)
+                        .Select(it => it.Trim())
+                        .Select(itemParser);
+            return results;
+        }
+
+        public static T? ToNullable<T>(this string s, Func<string, T> itemParser) where T : struct
+        {
+            T? result = new T?();
+            try
+            {
+                if (!string.IsNullOrEmpty(s) && s.Trim().Length > 0)
+                {
+                    result = itemParser(s);
+                }
+            }
+            catch (Exception e)
+            {
+                throw new InvalidOperationException(Strings.Format("Unable to parse value: '{0}' to nullable: '{1}'", s, typeof(T).ToString()), e);
+            }
+            return result;
+        }
+
         private class Parameter
         {
             internal string Name { get; private set; }
diff --git a/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/api/FakeApi.java b/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/api/FakeApi.java
index 50f6497e2f1..835b83c6234 100644
--- a/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/api/FakeApi.java
+++ b/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/api/FakeApi.java
@@ -1,8 +1,8 @@
 package io.swagger.api;
 
 import io.swagger.model.Client;
-import java.time.OffsetDateTime;
 import java.time.LocalDate;
+import java.time.OffsetDateTime;
 import java.math.BigDecimal;
 
 import io.swagger.annotations.*;
diff --git a/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/api/PetApi.java b/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/api/PetApi.java
index 6a8018d2c21..d87e7a68b65 100644
--- a/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/api/PetApi.java
+++ b/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/api/PetApi.java
@@ -1,8 +1,8 @@
 package io.swagger.api;
 
 import io.swagger.model.Pet;
-import io.swagger.model.ModelApiResponse;
 import java.io.File;
+import io.swagger.model.ModelApiResponse;
 
 import io.swagger.annotations.*;
 import org.springframework.http.HttpStatus;
diff --git a/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/model/HasOnlyReadOnly.java b/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/model/HasOnlyReadOnly.java
index 3f5492a2e62..55817f8dd14 100644
--- a/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/model/HasOnlyReadOnly.java
+++ b/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/model/HasOnlyReadOnly.java
@@ -17,6 +17,11 @@ public class HasOnlyReadOnly   {
   @JsonProperty("foo")
   private String foo = null;
 
+  public HasOnlyReadOnly bar(String bar) {
+    this.bar = bar;
+    return this;
+  }
+
    /**
    * Get bar
    * @return bar
@@ -26,6 +31,15 @@ public class HasOnlyReadOnly   {
     return bar;
   }
 
+  public void setBar(String bar) {
+    this.bar = bar;
+  }
+
+  public HasOnlyReadOnly foo(String foo) {
+    this.foo = foo;
+    return this;
+  }
+
    /**
    * Get foo
    * @return foo
@@ -35,6 +49,10 @@ public class HasOnlyReadOnly   {
     return foo;
   }
 
+  public void setFoo(String foo) {
+    this.foo = foo;
+  }
+
 
   @Override
   public boolean equals(java.lang.Object o) {
diff --git a/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/model/Name.java b/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/model/Name.java
index 09085fb52dc..aa31ac8d79a 100644
--- a/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/model/Name.java
+++ b/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/model/Name.java
@@ -42,6 +42,11 @@ public class Name   {
     this.name = name;
   }
 
+  public Name snakeCase(Integer snakeCase) {
+    this.snakeCase = snakeCase;
+    return this;
+  }
+
    /**
    * Get snakeCase
    * @return snakeCase
@@ -51,6 +56,10 @@ public class Name   {
     return snakeCase;
   }
 
+  public void setSnakeCase(Integer snakeCase) {
+    this.snakeCase = snakeCase;
+  }
+
   public Name property(String property) {
     this.property = property;
     return this;
@@ -69,6 +78,11 @@ public class Name   {
     this.property = property;
   }
 
+  public Name _123Number(Integer _123Number) {
+    this._123Number = _123Number;
+    return this;
+  }
+
    /**
    * Get _123Number
    * @return _123Number
@@ -78,6 +92,10 @@ public class Name   {
     return _123Number;
   }
 
+  public void set123Number(Integer _123Number) {
+    this._123Number = _123Number;
+  }
+
 
   @Override
   public boolean equals(java.lang.Object o) {
diff --git a/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/model/ReadOnlyFirst.java b/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/model/ReadOnlyFirst.java
index 50a2a7e4184..76d529c087a 100644
--- a/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/model/ReadOnlyFirst.java
+++ b/samples/server/petstore/spring-mvc-j8-async/src/main/java/io/swagger/model/ReadOnlyFirst.java
@@ -17,6 +17,11 @@ public class ReadOnlyFirst   {
   @JsonProperty("baz")
   private String baz = null;
 
+  public ReadOnlyFirst bar(String bar) {
+    this.bar = bar;
+    return this;
+  }
+
    /**
    * Get bar
    * @return bar
@@ -26,6 +31,10 @@ public class ReadOnlyFirst   {
     return bar;
   }
 
+  public void setBar(String bar) {
+    this.bar = bar;
+  }
+
   public ReadOnlyFirst baz(String baz) {
     this.baz = baz;
     return this;
diff --git a/samples/server/petstore/spring-mvc/src/main/java/io/swagger/api/PetApi.java b/samples/server/petstore/spring-mvc/src/main/java/io/swagger/api/PetApi.java
index 5b69114555e..3af82092a60 100644
--- a/samples/server/petstore/spring-mvc/src/main/java/io/swagger/api/PetApi.java
+++ b/samples/server/petstore/spring-mvc/src/main/java/io/swagger/api/PetApi.java
@@ -1,8 +1,8 @@
 package io.swagger.api;
 
 import io.swagger.model.Pet;
-import io.swagger.model.ModelApiResponse;
 import java.io.File;
+import io.swagger.model.ModelApiResponse;
 
 import io.swagger.annotations.*;
 import org.springframework.http.ResponseEntity;
diff --git a/samples/server/petstore/spring-mvc/src/main/java/io/swagger/api/PetApiController.java b/samples/server/petstore/spring-mvc/src/main/java/io/swagger/api/PetApiController.java
index 695d4cc2386..75de52391ac 100644
--- a/samples/server/petstore/spring-mvc/src/main/java/io/swagger/api/PetApiController.java
+++ b/samples/server/petstore/spring-mvc/src/main/java/io/swagger/api/PetApiController.java
@@ -1,8 +1,8 @@
 package io.swagger.api;
 
 import io.swagger.model.Pet;
-import io.swagger.model.ModelApiResponse;
 import java.io.File;
+import io.swagger.model.ModelApiResponse;
 
 import io.swagger.annotations.*;
 
diff --git a/samples/server/petstore/spring-mvc/src/main/java/io/swagger/model/HasOnlyReadOnly.java b/samples/server/petstore/spring-mvc/src/main/java/io/swagger/model/HasOnlyReadOnly.java
index 3f5492a2e62..55817f8dd14 100644
--- a/samples/server/petstore/spring-mvc/src/main/java/io/swagger/model/HasOnlyReadOnly.java
+++ b/samples/server/petstore/spring-mvc/src/main/java/io/swagger/model/HasOnlyReadOnly.java
@@ -17,6 +17,11 @@ public class HasOnlyReadOnly   {
   @JsonProperty("foo")
   private String foo = null;
 
+  public HasOnlyReadOnly bar(String bar) {
+    this.bar = bar;
+    return this;
+  }
+
    /**
    * Get bar
    * @return bar
@@ -26,6 +31,15 @@ public class HasOnlyReadOnly   {
     return bar;
   }
 
+  public void setBar(String bar) {
+    this.bar = bar;
+  }
+
+  public HasOnlyReadOnly foo(String foo) {
+    this.foo = foo;
+    return this;
+  }
+
    /**
    * Get foo
    * @return foo
@@ -35,6 +49,10 @@ public class HasOnlyReadOnly   {
     return foo;
   }
 
+  public void setFoo(String foo) {
+    this.foo = foo;
+  }
+
 
   @Override
   public boolean equals(java.lang.Object o) {
diff --git a/samples/server/petstore/spring-mvc/src/main/java/io/swagger/model/Name.java b/samples/server/petstore/spring-mvc/src/main/java/io/swagger/model/Name.java
index 09085fb52dc..aa31ac8d79a 100644
--- a/samples/server/petstore/spring-mvc/src/main/java/io/swagger/model/Name.java
+++ b/samples/server/petstore/spring-mvc/src/main/java/io/swagger/model/Name.java
@@ -42,6 +42,11 @@ public class Name   {
     this.name = name;
   }
 
+  public Name snakeCase(Integer snakeCase) {
+    this.snakeCase = snakeCase;
+    return this;
+  }
+
    /**
    * Get snakeCase
    * @return snakeCase
@@ -51,6 +56,10 @@ public class Name   {
     return snakeCase;
   }
 
+  public void setSnakeCase(Integer snakeCase) {
+    this.snakeCase = snakeCase;
+  }
+
   public Name property(String property) {
     this.property = property;
     return this;
@@ -69,6 +78,11 @@ public class Name   {
     this.property = property;
   }
 
+  public Name _123Number(Integer _123Number) {
+    this._123Number = _123Number;
+    return this;
+  }
+
    /**
    * Get _123Number
    * @return _123Number
@@ -78,6 +92,10 @@ public class Name   {
     return _123Number;
   }
 
+  public void set123Number(Integer _123Number) {
+    this._123Number = _123Number;
+  }
+
 
   @Override
   public boolean equals(java.lang.Object o) {
diff --git a/samples/server/petstore/spring-mvc/src/main/java/io/swagger/model/ReadOnlyFirst.java b/samples/server/petstore/spring-mvc/src/main/java/io/swagger/model/ReadOnlyFirst.java
index 50a2a7e4184..76d529c087a 100644
--- a/samples/server/petstore/spring-mvc/src/main/java/io/swagger/model/ReadOnlyFirst.java
+++ b/samples/server/petstore/spring-mvc/src/main/java/io/swagger/model/ReadOnlyFirst.java
@@ -17,6 +17,11 @@ public class ReadOnlyFirst   {
   @JsonProperty("baz")
   private String baz = null;
 
+  public ReadOnlyFirst bar(String bar) {
+    this.bar = bar;
+    return this;
+  }
+
    /**
    * Get bar
    * @return bar
@@ -26,6 +31,10 @@ public class ReadOnlyFirst   {
     return bar;
   }
 
+  public void setBar(String bar) {
+    this.bar = bar;
+  }
+
   public ReadOnlyFirst baz(String baz) {
     this.baz = baz;
     return this;
diff --git a/samples/server/petstore/springboot/src/main/java/io/swagger/api/PetApi.java b/samples/server/petstore/springboot/src/main/java/io/swagger/api/PetApi.java
index 5b69114555e..3af82092a60 100644
--- a/samples/server/petstore/springboot/src/main/java/io/swagger/api/PetApi.java
+++ b/samples/server/petstore/springboot/src/main/java/io/swagger/api/PetApi.java
@@ -1,8 +1,8 @@
 package io.swagger.api;
 
 import io.swagger.model.Pet;
-import io.swagger.model.ModelApiResponse;
 import java.io.File;
+import io.swagger.model.ModelApiResponse;
 
 import io.swagger.annotations.*;
 import org.springframework.http.ResponseEntity;
diff --git a/samples/server/petstore/springboot/src/main/java/io/swagger/api/PetApiController.java b/samples/server/petstore/springboot/src/main/java/io/swagger/api/PetApiController.java
index 695d4cc2386..75de52391ac 100644
--- a/samples/server/petstore/springboot/src/main/java/io/swagger/api/PetApiController.java
+++ b/samples/server/petstore/springboot/src/main/java/io/swagger/api/PetApiController.java
@@ -1,8 +1,8 @@
 package io.swagger.api;
 
 import io.swagger.model.Pet;
-import io.swagger.model.ModelApiResponse;
 import java.io.File;
+import io.swagger.model.ModelApiResponse;
 
 import io.swagger.annotations.*;
 
diff --git a/samples/server/petstore/springboot/src/main/java/io/swagger/model/HasOnlyReadOnly.java b/samples/server/petstore/springboot/src/main/java/io/swagger/model/HasOnlyReadOnly.java
index 3f5492a2e62..55817f8dd14 100644
--- a/samples/server/petstore/springboot/src/main/java/io/swagger/model/HasOnlyReadOnly.java
+++ b/samples/server/petstore/springboot/src/main/java/io/swagger/model/HasOnlyReadOnly.java
@@ -17,6 +17,11 @@ public class HasOnlyReadOnly   {
   @JsonProperty("foo")
   private String foo = null;
 
+  public HasOnlyReadOnly bar(String bar) {
+    this.bar = bar;
+    return this;
+  }
+
    /**
    * Get bar
    * @return bar
@@ -26,6 +31,15 @@ public class HasOnlyReadOnly   {
     return bar;
   }
 
+  public void setBar(String bar) {
+    this.bar = bar;
+  }
+
+  public HasOnlyReadOnly foo(String foo) {
+    this.foo = foo;
+    return this;
+  }
+
    /**
    * Get foo
    * @return foo
@@ -35,6 +49,10 @@ public class HasOnlyReadOnly   {
     return foo;
   }
 
+  public void setFoo(String foo) {
+    this.foo = foo;
+  }
+
 
   @Override
   public boolean equals(java.lang.Object o) {
diff --git a/samples/server/petstore/springboot/src/main/java/io/swagger/model/Name.java b/samples/server/petstore/springboot/src/main/java/io/swagger/model/Name.java
index 09085fb52dc..aa31ac8d79a 100644
--- a/samples/server/petstore/springboot/src/main/java/io/swagger/model/Name.java
+++ b/samples/server/petstore/springboot/src/main/java/io/swagger/model/Name.java
@@ -42,6 +42,11 @@ public class Name   {
     this.name = name;
   }
 
+  public Name snakeCase(Integer snakeCase) {
+    this.snakeCase = snakeCase;
+    return this;
+  }
+
    /**
    * Get snakeCase
    * @return snakeCase
@@ -51,6 +56,10 @@ public class Name   {
     return snakeCase;
   }
 
+  public void setSnakeCase(Integer snakeCase) {
+    this.snakeCase = snakeCase;
+  }
+
   public Name property(String property) {
     this.property = property;
     return this;
@@ -69,6 +78,11 @@ public class Name   {
     this.property = property;
   }
 
+  public Name _123Number(Integer _123Number) {
+    this._123Number = _123Number;
+    return this;
+  }
+
    /**
    * Get _123Number
    * @return _123Number
@@ -78,6 +92,10 @@ public class Name   {
     return _123Number;
   }
 
+  public void set123Number(Integer _123Number) {
+    this._123Number = _123Number;
+  }
+
 
   @Override
   public boolean equals(java.lang.Object o) {
diff --git a/samples/server/petstore/springboot/src/main/java/io/swagger/model/ReadOnlyFirst.java b/samples/server/petstore/springboot/src/main/java/io/swagger/model/ReadOnlyFirst.java
index 50a2a7e4184..76d529c087a 100644
--- a/samples/server/petstore/springboot/src/main/java/io/swagger/model/ReadOnlyFirst.java
+++ b/samples/server/petstore/springboot/src/main/java/io/swagger/model/ReadOnlyFirst.java
@@ -17,6 +17,11 @@ public class ReadOnlyFirst   {
   @JsonProperty("baz")
   private String baz = null;
 
+  public ReadOnlyFirst bar(String bar) {
+    this.bar = bar;
+    return this;
+  }
+
    /**
    * Get bar
    * @return bar
@@ -26,6 +31,10 @@ public class ReadOnlyFirst   {
     return bar;
   }
 
+  public void setBar(String bar) {
+    this.bar = bar;
+  }
+
   public ReadOnlyFirst baz(String baz) {
     this.baz = baz;
     return this;