diff --git a/modules/openapi-generator/src/main/resources/rust/Cargo.mustache b/modules/openapi-generator/src/main/resources/rust/Cargo.mustache
index 53c02a6f286..f8da736d432 100644
--- a/modules/openapi-generator/src/main/resources/rust/Cargo.mustache
+++ b/modules/openapi-generator/src/main/resources/rust/Cargo.mustache
@@ -10,10 +10,12 @@ serde_derive = "^1.0"
 serde_json = "^1.0"
 url = "^2.2"
 {{#hyper}}
-hyper = "~0.11"
+hyper = { version = "~0.14", features = ["full"] }
+hyper-tls = "~0.5"
+http = "~0.2"
 serde_yaml = "0.7"
 base64 = "~0.7.0"
-futures = "0.1.23"
+futures = "^0.3"
 {{/hyper}}
 {{#reqwest}}
 {{^supportAsync}}
diff --git a/modules/openapi-generator/src/main/resources/rust/hyper/api.mustache b/modules/openapi-generator/src/main/resources/rust/hyper/api.mustache
index e2833f16ed9..a055014fb5c 100644
--- a/modules/openapi-generator/src/main/resources/rust/hyper/api.mustache
+++ b/modules/openapi-generator/src/main/resources/rust/hyper/api.mustache
@@ -1,21 +1,23 @@
 {{>partial_header}}
 use std::rc::Rc;
 use std::borrow::Borrow;
+use std::pin::Pin;
 #[allow(unused_imports)]
 use std::option::Option;
 
 use hyper;
-use serde_json;
 use futures::Future;
 
 use super::{Error, configuration};
 use super::request as __internal_request;
 
-pub struct {{{classname}}}Client<C: hyper::client::Connect> {
+pub struct {{{classname}}}Client<C: hyper::client::connect::Connect>
+    where C: Clone + std::marker::Send + Sync + 'static {
     configuration: Rc<configuration::Configuration<C>>,
 }
 
-impl<C: hyper::client::Connect> {{{classname}}}Client<C> {
+impl<C: hyper::client::connect::Connect> {{{classname}}}Client<C>
+    where C: Clone + std::marker::Send + Sync {
     pub fn new(configuration: Rc<configuration::Configuration<C>>) -> {{{classname}}}Client<C> {
         {{{classname}}}Client {
             configuration,
@@ -26,16 +28,18 @@ impl<C: hyper::client::Connect> {{{classname}}}Client<C> {
 pub trait {{{classname}}} {
 {{#operations}}
 {{#operation}}
-    fn {{{operationId}}}(&self, {{#allParams}}{{{paramName}}}: {{^required}}Option<{{/required}}{{#required}}{{#isNullable}}Option<{{/isNullable}}{{/required}}{{#isString}}&str{{/isString}}{{#isUuid}}&str{{/isUuid}}{{^isString}}{{^isUuid}}{{^isPrimitiveType}}{{^isContainer}}crate::models::{{/isContainer}}{{/isPrimitiveType}}{{{dataType}}}{{/isUuid}}{{/isString}}{{^required}}>{{/required}}{{#required}}{{#isNullable}}>{{/isNullable}}{{/required}}{{^-last}}, {{/-last}}{{/allParams}}) -> Box<dyn Future<Item = {{^returnType}}(){{/returnType}}{{{returnType}}}, Error = Error<serde_json::Value>>>;
+    fn {{{operationId}}}(&self, {{#allParams}}{{{paramName}}}: {{^required}}Option<{{/required}}{{#required}}{{#isNullable}}Option<{{/isNullable}}{{/required}}{{#isString}}&str{{/isString}}{{#isUuid}}&str{{/isUuid}}{{^isString}}{{^isUuid}}{{^isPrimitiveType}}{{^isContainer}}crate::models::{{/isContainer}}{{/isPrimitiveType}}{{{dataType}}}{{/isUuid}}{{/isString}}{{^required}}>{{/required}}{{#required}}{{#isNullable}}>{{/isNullable}}{{/required}}{{^-last}}, {{/-last}}{{/allParams}}) -> Pin<Box<dyn Future<Output = Result<{{^returnType}}(){{/returnType}}{{#returnType}}{{{returnType}}}{{/returnType}}, Error>>>>;
 {{/operation}}
 {{/operations}}
 }
 
-impl<C: hyper::client::Connect>{{{classname}}} for {{{classname}}}Client<C> {
-{{#operations}}
-{{#operation}}
-    fn {{{operationId}}}(&self, {{#allParams}}{{{paramName}}}: {{^required}}Option<{{/required}}{{#required}}{{#isNullable}}Option<{{/isNullable}}{{/required}}{{#isString}}{{^isUuid}}&str{{/isUuid}}{{/isString}}{{#isUuid}}&str{{/isUuid}}{{^isString}}{{^isUuid}}{{^isPrimitiveType}}{{^isContainer}}crate::models::{{/isContainer}}{{/isPrimitiveType}}{{{dataType}}}{{/isUuid}}{{/isString}}{{^required}}>{{/required}}{{#required}}{{#isNullable}}>{{/isNullable}}{{/required}}{{^-last}}, {{/-last}}{{/allParams}}) -> Box<dyn Future<Item = {{^returnType}}(){{/returnType}}{{{returnType}}}, Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::{{{httpMethod}}}, "{{{path}}}".to_string())
+impl<C: hyper::client::connect::Connect>{{{classname}}} for {{{classname}}}Client<C>
+    where C: Clone + std::marker::Send + Sync {
+ {{#operations}}
+ {{#operation}}
+    #[allow(unused_mut)]
+    fn {{{operationId}}}(&self, {{#allParams}}{{{paramName}}}: {{^required}}Option<{{/required}}{{#required}}{{#isNullable}}Option<{{/isNullable}}{{/required}}{{#isString}}&str{{/isString}}{{#isUuid}}&str{{/isUuid}}{{^isString}}{{^isUuid}}{{^isPrimitiveType}}{{^isContainer}}crate::models::{{/isContainer}}{{/isPrimitiveType}}{{{dataType}}}{{/isUuid}}{{/isString}}{{^required}}>{{/required}}{{#required}}{{#isNullable}}>{{/isNullable}}{{/required}}{{^-last}}, {{/-last}}{{/allParams}}) -> Pin<Box<dyn Future<Output = Result<{{^returnType}}(){{/returnType}}{{#returnType}}{{{.}}}{{/returnType}}, Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::{{{httpMethod.toUpperCase}}}, "{{{path}}}".to_string())
         {{#hasAuthMethods}}
         {{#authMethods}}
         {{#isApiKey}}
@@ -68,7 +72,8 @@ impl<C: hyper::client::Connect>{{{classname}}} for {{{classname}}}Client<C> {
         {{/required}}
         {{^required}}
         if let Some(ref s) = {{{paramName}}} {
-            req = req.with_query_param("{{{baseName}}}".to_string(), s{{#isArray}}.join(","){{/isArray}}.to_string());
+            let query_value = {{#isArray}}s.iter().map(|s| s.to_string()).collect::<Vec<String>>().join(","){{/isArray}}{{^isArray}}s.to_string(){{/isArray}};
+            req = req.with_query_param("{{{baseName}}}".to_string(), query_value);
         }
         {{/required}}
         {{/queryParams}}
diff --git a/modules/openapi-generator/src/main/resources/rust/hyper/api_mod.mustache b/modules/openapi-generator/src/main/resources/rust/hyper/api_mod.mustache
index 4f220c93d56..8314cb60b07 100644
--- a/modules/openapi-generator/src/main/resources/rust/hyper/api_mod.mustache
+++ b/modules/openapi-generator/src/main/resources/rust/hyper/api_mod.mustache
@@ -1,49 +1,45 @@
+use http;
 use hyper;
-use serde;
 use serde_json;
 
 #[derive(Debug)]
-pub enum Error<T> {
-    UriError(hyper::error::UriError),
+pub enum Error {
+    Api(ApiError),
+    Header(hyper::http::header::InvalidHeaderValue),
+    Http(http::Error),
     Hyper(hyper::Error),
     Serde(serde_json::Error),
-    ApiError(ApiError<T>),
+    UriError(http::uri::InvalidUri),
 }
 
 #[derive(Debug)]
-pub struct ApiError<T> {
+pub struct ApiError {
     pub code: hyper::StatusCode,
-    pub content: Option<T>,
+    pub body: hyper::body::Body,
 }
 
-impl<'de, T> From<(hyper::StatusCode, &'de [u8])> for Error<T>
-    where T: serde::Deserialize<'de> {
-    fn from(e: (hyper::StatusCode, &'de [u8])) -> Self {
-        if e.1.len() == 0 {
-            return Error::ApiError(ApiError{
-                code: e.0,
-                content: None,
-            });
-        }
-        match serde_json::from_slice::<T>(e.1) {
-            Ok(t) => Error::ApiError(ApiError{
-                code: e.0,
-                content: Some(t),
-            }),
-            Err(e) => {
-                Error::from(e)
-            }
-        }
+impl From<(hyper::StatusCode, hyper::body::Body)> for Error {
+    fn from(e: (hyper::StatusCode, hyper::body::Body)) -> Self {
+        Error::Api(ApiError {
+            code: e.0,
+            body: e.1,
+        })
     }
 }
 
-impl<T> From<hyper::Error> for Error<T> {
+impl From<http::Error> for Error {
+    fn from(e: http::Error) -> Self {
+        return Error::Http(e)
+    }
+}
+
+impl From<hyper::Error> for Error {
     fn from(e: hyper::Error) -> Self {
         return Error::Hyper(e)
     }
 }
 
-impl<T> From<serde_json::Error> for Error<T> {
+impl From<serde_json::Error> for Error {
     fn from(e: serde_json::Error) -> Self {
         return Error::Serde(e)
     }
diff --git a/modules/openapi-generator/src/main/resources/rust/hyper/client.mustache b/modules/openapi-generator/src/main/resources/rust/hyper/client.mustache
index 5b3bcf85c75..25124d94b36 100644
--- a/modules/openapi-generator/src/main/resources/rust/hyper/client.mustache
+++ b/modules/openapi-generator/src/main/resources/rust/hyper/client.mustache
@@ -18,7 +18,8 @@ pub struct APIClient {
 }
 
 impl APIClient {
-    pub fn new<C: hyper::client::Connect>(configuration: Configuration<C>) -> APIClient {
+    pub fn new<C: hyper::client::connect::Connect>(configuration: Configuration<C>) -> APIClient
+        where C: Clone + std::marker::Send + Sync + 'static {
         let rc = Rc::new(configuration);
 
         APIClient {
diff --git a/modules/openapi-generator/src/main/resources/rust/hyper/configuration.mustache b/modules/openapi-generator/src/main/resources/rust/hyper/configuration.mustache
index adb51d6e92c..ee6f407d31b 100644
--- a/modules/openapi-generator/src/main/resources/rust/hyper/configuration.mustache
+++ b/modules/openapi-generator/src/main/resources/rust/hyper/configuration.mustache
@@ -1,7 +1,8 @@
 {{>partial_header}}
 use hyper;
 
-pub struct Configuration<C: hyper::client::Connect> {
+pub struct Configuration<C: hyper::client::connect::Connect>
+    where C: Clone + std::marker::Send + Sync + 'static {
     pub base_path: String,
     pub user_agent: Option<String>,
     pub client: hyper::client::Client<C>,
@@ -18,12 +19,13 @@ pub struct ApiKey {
     pub key: String,
 }
 
-impl<C: hyper::client::Connect> Configuration<C> {
+impl<C: hyper::client::connect::Connect> Configuration<C>
+    where C: Clone + std::marker::Send + Sync {
     pub fn new(client: hyper::client::Client<C>) -> Configuration<C> {
         Configuration {
             base_path: "{{{basePath}}}".to_owned(),
             user_agent: {{#httpUserAgent}}Some("{{{.}}}".to_owned()){{/httpUserAgent}}{{^httpUserAgent}}Some("OpenAPI-Generator/{{{version}}}/rust".to_owned()){{/httpUserAgent}},
-            client: client,
+            client,
             basic_auth: None,
             oauth_access_token: None,
             api_key: None,
diff --git a/modules/openapi-generator/src/main/resources/rust/request.rs b/modules/openapi-generator/src/main/resources/rust/request.rs
index f97b5277196..0aa51fa0c59 100644
--- a/modules/openapi-generator/src/main/resources/rust/request.rs
+++ b/modules/openapi-generator/src/main/resources/rust/request.rs
@@ -1,14 +1,16 @@
-use std::borrow::Cow;
 use std::collections::HashMap;
+use std::pin::Pin;
 
-use super::{configuration, Error};
 use futures;
-use futures::{Future, Stream};
+use futures::Future;
+use futures::future::*;
 use hyper;
-use hyper::header::UserAgent;
+use hyper::header::{AUTHORIZATION, CONTENT_LENGTH, CONTENT_TYPE, HeaderValue, USER_AGENT};
 use serde;
 use serde_json;
 
+use super::{configuration, Error};
+
 pub(crate) struct ApiKey {
     pub in_header: bool,
     pub in_query: bool,
@@ -32,8 +34,11 @@ pub(crate) enum Auth {
     Oauth,
 }
 
+/// If the authorization type is unspecified then it will be automatically detected based
+/// on the configuration. This functionality is useful when the OpenAPI definition does not
+/// include an authorization scheme.
 pub(crate) struct Request {
-    auth: Auth,
+    auth: Option<Auth>,
     method: hyper::Method,
     path: String,
     query_params: HashMap<String, String>,
@@ -48,9 +53,9 @@ pub(crate) struct Request {
 impl Request {
     pub fn new(method: hyper::Method, path: String) -> Self {
         Request {
-            auth: Auth::None,
-            method: method,
-            path: path,
+            auth: None,
+            method,
+            path,
             query_params: HashMap::new(),
             path_params: HashMap::new(),
             form_params: HashMap::new(),
@@ -91,24 +96,20 @@ impl Request {
     }
 
     pub fn with_auth(mut self, auth: Auth) -> Self {
-        self.auth = auth;
+        self.auth = Some(auth);
         self
     }
 
     pub fn execute<'a, C, U>(
         self,
         conf: &configuration::Configuration<C>,
-    ) -> Box<dyn Future<Item = U, Error = Error<serde_json::Value>> + 'a>
-    where
-        C: hyper::client::Connect,
-        U: Sized + 'a,
-        for<'de> U: serde::Deserialize<'de>,
+    ) -> Pin<Box<dyn Future<Output=Result<U, Error>> + 'a>>
+        where
+            C: hyper::client::connect::Connect + Clone + std::marker::Send + Sync,
+            U: Sized + std::marker::Send + 'a,
+            for<'de> U: serde::Deserialize<'de>,
     {
         let mut query_string = ::url::form_urlencoded::Serializer::new("".to_owned());
-        // raw_headers is for headers we don't know the proper type of (e.g. custom api key
-        // headers); headers is for ones we do know the type of.
-        let mut raw_headers = HashMap::new();
-        let mut headers: hyper::header::Headers = hyper::header::Headers::new();
 
         let mut path = self.path;
         for (k, v) in self.path_params {
@@ -116,46 +117,10 @@ impl Request {
             path = path.replace(&format!("{{{}}}", k), &v);
         }
 
-        for (k, v) in self.header_params {
-            raw_headers.insert(k, v);
-        }
-
         for (key, val) in self.query_params {
             query_string.append_pair(&key, &val);
         }
 
-        match self.auth {
-            Auth::ApiKey(apikey) => {
-                if let Some(ref key) = conf.api_key {
-                    let val = apikey.key(&key.prefix, &key.key);
-                    if apikey.in_query {
-                        query_string.append_pair(&apikey.param_name, &val);
-                    }
-                    if apikey.in_header {
-                        raw_headers.insert(apikey.param_name, val);
-                    }
-                }
-            }
-            Auth::Basic => {
-                if let Some(ref auth_conf) = conf.basic_auth {
-                    let auth = hyper::header::Authorization(hyper::header::Basic {
-                        username: auth_conf.0.to_owned(),
-                        password: auth_conf.1.to_owned(),
-                    });
-                    headers.set(auth);
-                }
-            }
-            Auth::Oauth => {
-                if let Some(ref token) = conf.oauth_access_token {
-                    let auth = hyper::header::Authorization(hyper::header::Bearer {
-                        token: token.to_owned(),
-                    });
-                    headers.set(auth);
-                }
-            }
-            Auth::None => {}
-        }
-
         let mut uri_str = format!("{}{}", conf.base_path, path);
 
         let query_string_str = query_string.finish();
@@ -164,76 +129,110 @@ impl Request {
             uri_str += &query_string_str;
         }
         let uri: hyper::Uri = match uri_str.parse() {
-            Err(e) => {
-                return Box::new(futures::future::err(Error::UriError(e)));
-            }
+            Err(e) => return Box::pin(futures::future::err(Error::UriError(e))),
             Ok(u) => u,
         };
 
-        let mut req = hyper::Request::new(self.method, uri);
-        {
-            let req_headers = req.headers_mut();
-            if let Some(ref user_agent) = conf.user_agent {
-                req_headers.set(UserAgent::new(Cow::Owned(user_agent.clone())));
-            }
+        let mut req_builder = hyper::Request::builder()
+            .uri(uri)
+            .method(self.method);
 
-            req_headers.extend(headers.iter());
-
-            for (key, val) in raw_headers {
-                req_headers.set_raw(key, val);
+        // Detect the authorization type if it hasn't been set.
+        let auth = self.auth.unwrap_or_else(||
+            if conf.api_key.is_some() {
+                panic!("Cannot automatically set the API key from the configuration, it must be specified in the OpenAPI definition")
+            } else if conf.oauth_access_token.is_some() {
+                Auth::Oauth
+            } else if conf.basic_auth.is_some() {
+                Auth::Basic
+            } else {
+                Auth::None
             }
+        );
+        match auth {
+            Auth::ApiKey(apikey) => {
+                if let Some(ref key) = conf.api_key {
+                    let val = apikey.key(&key.prefix, &key.key);
+                    if apikey.in_query {
+                        query_string.append_pair(&apikey.param_name, &val);
+                    }
+                    if apikey.in_header {
+                        req_builder = req_builder.header(&apikey.param_name, val);
+                    }
+                }
+            }
+            Auth::Basic => {
+                if let Some(ref auth_conf) = conf.basic_auth {
+                    let mut text = auth_conf.0.clone();
+                    text.push(':');
+                    if let Some(ref pass) = auth_conf.1 {
+                        text.push_str(&pass[..]);
+                    }
+                    let encoded = base64::encode(&text);
+                    req_builder = req_builder.header(AUTHORIZATION, encoded);
+                }
+            }
+            Auth::Oauth => {
+                if let Some(ref token) = conf.oauth_access_token {
+                    let text = "Bearer ".to_owned() + token;
+                    req_builder = req_builder.header(AUTHORIZATION, text);
+                }
+            }
+            Auth::None => {}
         }
 
-        if self.form_params.len() > 0 {
-            req.headers_mut().set(hyper::header::ContentType::form_url_encoded());
+        if let Some(ref user_agent) = conf.user_agent {
+            req_builder = req_builder.header(USER_AGENT, match HeaderValue::from_str(user_agent) {
+                Ok(header_value) => header_value,
+                Err(e) => return Box::pin(futures::future::err(super::Error::Header(e)))
+            });
+        }
+
+        for (k, v) in self.header_params {
+            req_builder = req_builder.header(&k, v);
+        }
+
+        let req_headers = req_builder.headers_mut().unwrap();
+        let request_result = if self.form_params.len() > 0 {
+            req_headers.insert(CONTENT_TYPE, HeaderValue::from_static("application/ x-www-form-urlencoded"));
             let mut enc = ::url::form_urlencoded::Serializer::new("".to_owned());
             for (k, v) in self.form_params {
                 enc.append_pair(&k, &v);
             }
-            req.set_body(enc.finish());
-        }
+            req_builder.body(hyper::Body::from(enc.finish()))
+        } else if let Some(body) = self.serialized_body {
+            req_headers.insert(CONTENT_TYPE, HeaderValue::from_static("application/json"));
+            req_headers.insert(CONTENT_LENGTH, body.len().into());
+            req_builder.body(hyper::Body::from(body))
+        } else {
+            req_builder.body(hyper::Body::default())
+        };
+        let request = match request_result {
+            Ok(request) => request,
+            Err(e) => return Box::pin(futures::future::err(Error::from(e)))
+        };
 
-        if let Some(body) = self.serialized_body {
-            req.headers_mut().set(hyper::header::ContentType::json());
-            req.headers_mut()
-                .set(hyper::header::ContentLength(body.len() as u64));
-            req.set_body(body);
-        }
-
-        let no_ret_type = self.no_return_type;
-        let res = conf.client
-                .request(req)
-                .map_err(|e| Error::from(e))
-                .and_then(|resp| {
-                    let status = resp.status();
-                    resp.body()
-                        .concat2()
-                        .and_then(move |body| Ok((status, body)))
-                        .map_err(|e| Error::from(e))
-                })
-                .and_then(|(status, body)| {
-                    if status.is_success() {
-                        Ok(body)
-                    } else {
-                        Err(Error::from((status, &*body)))
-                    }
-                });
-        Box::new(
-            res
-                .and_then(move |body| {
-                    let parsed: Result<U, _> = if no_ret_type {
-                        // This is a hack; if there's no_ret_type, U is (), but serde_json gives an
-                        // error when deserializing "" into (), so deserialize 'null' into it
-                        // instead.
-                        // An alternate option would be to require U: Default, and then return
-                        // U::default() here instead since () implements that, but then we'd
-                        // need to impl default for all models.
-                        serde_json::from_str("null")
-                    } else {
-                        serde_json::from_slice(&body)
-                    };
-                    parsed.map_err(|e| Error::from(e))
-                })
-        )
+        let no_return_type = self.no_return_type;
+        Box::pin(conf.client
+            .request(request)
+            .map_err(|e| Error::from(e))
+            .and_then(move |response| {
+                let status = response.status();
+                if !status.is_success() {
+                    futures::future::err::<U, Error>(Error::from((status, response.into_body()))).boxed()
+                } else if no_return_type {
+                    // This is a hack; if there's no_ret_type, U is (), but serde_json gives an
+                    // error when deserializing "" into (), so deserialize 'null' into it
+                    // instead.
+                    // An alternate option would be to require U: Default, and then return
+                    // U::default() here instead since () implements that, but then we'd
+                    // need to impl default for all models.
+                    futures::future::ok::<U, Error>(serde_json::from_str("null").expect("serde null value")).boxed()
+                } else {
+                    hyper::body::to_bytes(response.into_body())
+                        .map(|bytes| serde_json::from_slice(&bytes.unwrap()))
+                        .map_err(|e| Error::from(e)).boxed()
+                }
+            }))
     }
 }
diff --git a/samples/client/petstore/rust/hyper/petstore/Cargo.toml b/samples/client/petstore/rust/hyper/petstore/Cargo.toml
index 4bed4953a55..443de5b186a 100644
--- a/samples/client/petstore/rust/hyper/petstore/Cargo.toml
+++ b/samples/client/petstore/rust/hyper/petstore/Cargo.toml
@@ -9,10 +9,12 @@ serde = "^1.0"
 serde_derive = "^1.0"
 serde_json = "^1.0"
 url = "^2.2"
-hyper = "~0.11"
+hyper = { version = "~0.14", features = ["full"] }
+hyper-tls = "~0.5"
+http = "~0.2"
 serde_yaml = "0.7"
 base64 = "~0.7.0"
-futures = "0.1.23"
+futures = "^0.3"
 
 [dev-dependencies]
 tokio-core = "*"
diff --git a/samples/client/petstore/rust/hyper/petstore/src/apis/client.rs b/samples/client/petstore/rust/hyper/petstore/src/apis/client.rs
index 34953d4a063..290b99e86f3 100644
--- a/samples/client/petstore/rust/hyper/petstore/src/apis/client.rs
+++ b/samples/client/petstore/rust/hyper/petstore/src/apis/client.rs
@@ -10,7 +10,8 @@ pub struct APIClient {
 }
 
 impl APIClient {
-    pub fn new<C: hyper::client::Connect>(configuration: Configuration<C>) -> APIClient {
+    pub fn new<C: hyper::client::connect::Connect>(configuration: Configuration<C>) -> APIClient
+        where C: Clone + std::marker::Send + Sync + 'static {
         let rc = Rc::new(configuration);
 
         APIClient {
diff --git a/samples/client/petstore/rust/hyper/petstore/src/apis/configuration.rs b/samples/client/petstore/rust/hyper/petstore/src/apis/configuration.rs
index 83d5f1c3d0c..ae41a752976 100644
--- a/samples/client/petstore/rust/hyper/petstore/src/apis/configuration.rs
+++ b/samples/client/petstore/rust/hyper/petstore/src/apis/configuration.rs
@@ -10,7 +10,8 @@
 
 use hyper;
 
-pub struct Configuration<C: hyper::client::Connect> {
+pub struct Configuration<C: hyper::client::connect::Connect>
+    where C: Clone + std::marker::Send + Sync + 'static {
     pub base_path: String,
     pub user_agent: Option<String>,
     pub client: hyper::client::Client<C>,
@@ -27,12 +28,13 @@ pub struct ApiKey {
     pub key: String,
 }
 
-impl<C: hyper::client::Connect> Configuration<C> {
+impl<C: hyper::client::connect::Connect> Configuration<C>
+    where C: Clone + std::marker::Send + Sync {
     pub fn new(client: hyper::client::Client<C>) -> Configuration<C> {
         Configuration {
             base_path: "http://petstore.swagger.io/v2".to_owned(),
             user_agent: Some("OpenAPI-Generator/1.0.0/rust".to_owned()),
-            client: client,
+            client,
             basic_auth: None,
             oauth_access_token: None,
             api_key: None,
diff --git a/samples/client/petstore/rust/hyper/petstore/src/apis/mod.rs b/samples/client/petstore/rust/hyper/petstore/src/apis/mod.rs
index c9d96c29fd0..1245257e5d8 100644
--- a/samples/client/petstore/rust/hyper/petstore/src/apis/mod.rs
+++ b/samples/client/petstore/rust/hyper/petstore/src/apis/mod.rs
@@ -1,49 +1,45 @@
+use http;
 use hyper;
-use serde;
 use serde_json;
 
 #[derive(Debug)]
-pub enum Error<T> {
-    UriError(hyper::error::UriError),
+pub enum Error {
+    Api(ApiError),
+    Header(hyper::http::header::InvalidHeaderValue),
+    Http(http::Error),
     Hyper(hyper::Error),
     Serde(serde_json::Error),
-    ApiError(ApiError<T>),
+    UriError(http::uri::InvalidUri),
 }
 
 #[derive(Debug)]
-pub struct ApiError<T> {
+pub struct ApiError {
     pub code: hyper::StatusCode,
-    pub content: Option<T>,
+    pub body: hyper::body::Body,
 }
 
-impl<'de, T> From<(hyper::StatusCode, &'de [u8])> for Error<T>
-    where T: serde::Deserialize<'de> {
-    fn from(e: (hyper::StatusCode, &'de [u8])) -> Self {
-        if e.1.len() == 0 {
-            return Error::ApiError(ApiError{
-                code: e.0,
-                content: None,
-            });
-        }
-        match serde_json::from_slice::<T>(e.1) {
-            Ok(t) => Error::ApiError(ApiError{
-                code: e.0,
-                content: Some(t),
-            }),
-            Err(e) => {
-                Error::from(e)
-            }
-        }
+impl From<(hyper::StatusCode, hyper::body::Body)> for Error {
+    fn from(e: (hyper::StatusCode, hyper::body::Body)) -> Self {
+        Error::Api(ApiError {
+            code: e.0,
+            body: e.1,
+        })
     }
 }
 
-impl<T> From<hyper::Error> for Error<T> {
+impl From<http::Error> for Error {
+    fn from(e: http::Error) -> Self {
+        return Error::Http(e)
+    }
+}
+
+impl From<hyper::Error> for Error {
     fn from(e: hyper::Error) -> Self {
         return Error::Hyper(e)
     }
 }
 
-impl<T> From<serde_json::Error> for Error<T> {
+impl From<serde_json::Error> for Error {
     fn from(e: serde_json::Error) -> Self {
         return Error::Serde(e)
     }
diff --git a/samples/client/petstore/rust/hyper/petstore/src/apis/pet_api.rs b/samples/client/petstore/rust/hyper/petstore/src/apis/pet_api.rs
index f1bdaf0e89a..3d90eae36b3 100644
--- a/samples/client/petstore/rust/hyper/petstore/src/apis/pet_api.rs
+++ b/samples/client/petstore/rust/hyper/petstore/src/apis/pet_api.rs
@@ -4,27 +4,29 @@
  * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
  *
  * The version of the OpenAPI document: 1.0.0
- * 
+ *
  * Generated by: https://openapi-generator.tech
  */
 
 use std::rc::Rc;
 use std::borrow::Borrow;
+use std::pin::Pin;
 #[allow(unused_imports)]
 use std::option::Option;
 
 use hyper;
-use serde_json;
 use futures::Future;
 
 use super::{Error, configuration};
 use super::request as __internal_request;
 
-pub struct PetApiClient<C: hyper::client::Connect> {
+pub struct PetApiClient<C: hyper::client::connect::Connect>
+    where C: Clone + std::marker::Send + Sync + 'static {
     configuration: Rc<configuration::Configuration<C>>,
 }
 
-impl<C: hyper::client::Connect> PetApiClient<C> {
+impl<C: hyper::client::connect::Connect> PetApiClient<C>
+    where C: Clone + std::marker::Send + Sync {
     pub fn new(configuration: Rc<configuration::Configuration<C>>) -> PetApiClient<C> {
         PetApiClient {
             configuration,
@@ -33,19 +35,21 @@ impl<C: hyper::client::Connect> PetApiClient<C> {
 }
 
 pub trait PetApi {
-    fn add_pet(&self, pet: crate::models::Pet) -> Box<dyn Future<Item = crate::models::Pet, Error = Error<serde_json::Value>>>;
-    fn delete_pet(&self, pet_id: i64, api_key: Option<&str>) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>>;
-    fn find_pets_by_status(&self, status: Vec<String>) -> Box<dyn Future<Item = Vec<crate::models::Pet>, Error = Error<serde_json::Value>>>;
-    fn find_pets_by_tags(&self, tags: Vec<String>) -> Box<dyn Future<Item = Vec<crate::models::Pet>, Error = Error<serde_json::Value>>>;
-    fn get_pet_by_id(&self, pet_id: i64) -> Box<dyn Future<Item = crate::models::Pet, Error = Error<serde_json::Value>>>;
-    fn update_pet(&self, pet: crate::models::Pet) -> Box<dyn Future<Item = crate::models::Pet, Error = Error<serde_json::Value>>>;
-    fn update_pet_with_form(&self, pet_id: i64, name: Option<&str>, status: Option<&str>) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>>;
-    fn upload_file(&self, pet_id: i64, additional_metadata: Option<&str>, file: Option<std::path::PathBuf>) -> Box<dyn Future<Item = crate::models::ApiResponse, Error = Error<serde_json::Value>>>;
+    fn add_pet(&self, body: crate::models::Pet) -> Pin<Box<dyn Future<Output = Result<(), Error>>>>;
+    fn delete_pet(&self, pet_id: i64, api_key: Option<&str>) -> Pin<Box<dyn Future<Output = Result<(), Error>>>>;
+    fn find_pets_by_status(&self, status: Vec<String>) -> Pin<Box<dyn Future<Output = Result<Vec<crate::models::Pet>, Error>>>>;
+    fn find_pets_by_tags(&self, tags: Vec<String>) -> Pin<Box<dyn Future<Output = Result<Vec<crate::models::Pet>, Error>>>>;
+    fn get_pet_by_id(&self, pet_id: i64) -> Pin<Box<dyn Future<Output = Result<crate::models::Pet, Error>>>>;
+    fn update_pet(&self, body: crate::models::Pet) -> Pin<Box<dyn Future<Output = Result<(), Error>>>>;
+    fn update_pet_with_form(&self, pet_id: i64, name: Option<&str>, status: Option<&str>) -> Pin<Box<dyn Future<Output = Result<(), Error>>>>;
+    fn upload_file(&self, pet_id: i64, additional_metadata: Option<&str>, file: Option<std::path::PathBuf>) -> Pin<Box<dyn Future<Output = Result<crate::models::ApiResponse, Error>>>>;
 }
 
-impl<C: hyper::client::Connect>PetApi for PetApiClient<C> {
-    fn add_pet(&self, pet: crate::models::Pet) -> Box<dyn Future<Item = crate::models::Pet, Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Post, "/pet".to_string())
+impl<C: hyper::client::connect::Connect>PetApi for PetApiClient<C>
+    where C: Clone + std::marker::Send + Sync {
+    #[allow(unused_mut)]
+    fn add_pet(&self, body: crate::models::Pet) -> Pin<Box<dyn Future<Output = Result<(), Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::POST, "/pet".to_string())
             .with_auth(__internal_request::Auth::Oauth)
         ;
         req = req.with_body_param(pet);
@@ -53,8 +57,9 @@ impl<C: hyper::client::Connect>PetApi for PetApiClient<C> {
         req.execute(self.configuration.borrow())
     }
 
-    fn delete_pet(&self, pet_id: i64, api_key: Option<&str>) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Delete, "/pet/{petId}".to_string())
+    #[allow(unused_mut)]
+    fn delete_pet(&self, pet_id: i64, api_key: Option<&str>) -> Pin<Box<dyn Future<Output = Result<(), Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::DELETE, "/pet/{petId}".to_string())
             .with_auth(__internal_request::Auth::Oauth)
         ;
         req = req.with_path_param("petId".to_string(), pet_id.to_string());
@@ -66,8 +71,9 @@ impl<C: hyper::client::Connect>PetApi for PetApiClient<C> {
         req.execute(self.configuration.borrow())
     }
 
-    fn find_pets_by_status(&self, status: Vec<String>) -> Box<dyn Future<Item = Vec<crate::models::Pet>, Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Get, "/pet/findByStatus".to_string())
+    #[allow(unused_mut)]
+    fn find_pets_by_status(&self, status: Vec<String>) -> Pin<Box<dyn Future<Output = Result<Vec<crate::models::Pet>, Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::GET, "/pet/findByStatus".to_string())
             .with_auth(__internal_request::Auth::Oauth)
         ;
         req = req.with_query_param("status".to_string(), status.join(",").to_string());
@@ -75,8 +81,9 @@ impl<C: hyper::client::Connect>PetApi for PetApiClient<C> {
         req.execute(self.configuration.borrow())
     }
 
-    fn find_pets_by_tags(&self, tags: Vec<String>) -> Box<dyn Future<Item = Vec<crate::models::Pet>, Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Get, "/pet/findByTags".to_string())
+    #[allow(unused_mut)]
+    fn find_pets_by_tags(&self, tags: Vec<String>) -> Pin<Box<dyn Future<Output = Result<Vec<crate::models::Pet>, Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::GET, "/pet/findByTags".to_string())
             .with_auth(__internal_request::Auth::Oauth)
         ;
         req = req.with_query_param("tags".to_string(), tags.join(",").to_string());
@@ -84,8 +91,9 @@ impl<C: hyper::client::Connect>PetApi for PetApiClient<C> {
         req.execute(self.configuration.borrow())
     }
 
-    fn get_pet_by_id(&self, pet_id: i64) -> Box<dyn Future<Item = crate::models::Pet, Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Get, "/pet/{petId}".to_string())
+    #[allow(unused_mut)]
+    fn get_pet_by_id(&self, pet_id: i64) -> Pin<Box<dyn Future<Output = Result<crate::models::Pet, Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::GET, "/pet/{petId}".to_string())
             .with_auth(__internal_request::Auth::ApiKey(__internal_request::ApiKey{
                 in_header: true,
                 in_query: false,
@@ -97,8 +105,9 @@ impl<C: hyper::client::Connect>PetApi for PetApiClient<C> {
         req.execute(self.configuration.borrow())
     }
 
-    fn update_pet(&self, pet: crate::models::Pet) -> Box<dyn Future<Item = crate::models::Pet, Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Put, "/pet".to_string())
+    #[allow(unused_mut)]
+    fn update_pet(&self, body: crate::models::Pet) -> Pin<Box<dyn Future<Output = Result<(), Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::PUT, "/pet".to_string())
             .with_auth(__internal_request::Auth::Oauth)
         ;
         req = req.with_body_param(pet);
@@ -106,8 +115,9 @@ impl<C: hyper::client::Connect>PetApi for PetApiClient<C> {
         req.execute(self.configuration.borrow())
     }
 
-    fn update_pet_with_form(&self, pet_id: i64, name: Option<&str>, status: Option<&str>) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Post, "/pet/{petId}".to_string())
+    #[allow(unused_mut)]
+    fn update_pet_with_form(&self, pet_id: i64, name: Option<&str>, status: Option<&str>) -> Pin<Box<dyn Future<Output = Result<(), Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::POST, "/pet/{petId}".to_string())
             .with_auth(__internal_request::Auth::Oauth)
         ;
         req = req.with_path_param("petId".to_string(), pet_id.to_string());
@@ -122,8 +132,9 @@ impl<C: hyper::client::Connect>PetApi for PetApiClient<C> {
         req.execute(self.configuration.borrow())
     }
 
-    fn upload_file(&self, pet_id: i64, additional_metadata: Option<&str>, file: Option<std::path::PathBuf>) -> Box<dyn Future<Item = crate::models::ApiResponse, Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Post, "/pet/{petId}/uploadImage".to_string())
+    #[allow(unused_mut)]
+    fn upload_file(&self, pet_id: i64, additional_metadata: Option<&str>, file: Option<std::path::PathBuf>) -> Pin<Box<dyn Future<Output = Result<crate::models::ApiResponse, Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::POST, "/pet/{petId}/uploadImage".to_string())
             .with_auth(__internal_request::Auth::Oauth)
         ;
         req = req.with_path_param("petId".to_string(), pet_id.to_string());
diff --git a/samples/client/petstore/rust/hyper/petstore/src/apis/request.rs b/samples/client/petstore/rust/hyper/petstore/src/apis/request.rs
index f97b5277196..0aa51fa0c59 100644
--- a/samples/client/petstore/rust/hyper/petstore/src/apis/request.rs
+++ b/samples/client/petstore/rust/hyper/petstore/src/apis/request.rs
@@ -1,14 +1,16 @@
-use std::borrow::Cow;
 use std::collections::HashMap;
+use std::pin::Pin;
 
-use super::{configuration, Error};
 use futures;
-use futures::{Future, Stream};
+use futures::Future;
+use futures::future::*;
 use hyper;
-use hyper::header::UserAgent;
+use hyper::header::{AUTHORIZATION, CONTENT_LENGTH, CONTENT_TYPE, HeaderValue, USER_AGENT};
 use serde;
 use serde_json;
 
+use super::{configuration, Error};
+
 pub(crate) struct ApiKey {
     pub in_header: bool,
     pub in_query: bool,
@@ -32,8 +34,11 @@ pub(crate) enum Auth {
     Oauth,
 }
 
+/// If the authorization type is unspecified then it will be automatically detected based
+/// on the configuration. This functionality is useful when the OpenAPI definition does not
+/// include an authorization scheme.
 pub(crate) struct Request {
-    auth: Auth,
+    auth: Option<Auth>,
     method: hyper::Method,
     path: String,
     query_params: HashMap<String, String>,
@@ -48,9 +53,9 @@ pub(crate) struct Request {
 impl Request {
     pub fn new(method: hyper::Method, path: String) -> Self {
         Request {
-            auth: Auth::None,
-            method: method,
-            path: path,
+            auth: None,
+            method,
+            path,
             query_params: HashMap::new(),
             path_params: HashMap::new(),
             form_params: HashMap::new(),
@@ -91,24 +96,20 @@ impl Request {
     }
 
     pub fn with_auth(mut self, auth: Auth) -> Self {
-        self.auth = auth;
+        self.auth = Some(auth);
         self
     }
 
     pub fn execute<'a, C, U>(
         self,
         conf: &configuration::Configuration<C>,
-    ) -> Box<dyn Future<Item = U, Error = Error<serde_json::Value>> + 'a>
-    where
-        C: hyper::client::Connect,
-        U: Sized + 'a,
-        for<'de> U: serde::Deserialize<'de>,
+    ) -> Pin<Box<dyn Future<Output=Result<U, Error>> + 'a>>
+        where
+            C: hyper::client::connect::Connect + Clone + std::marker::Send + Sync,
+            U: Sized + std::marker::Send + 'a,
+            for<'de> U: serde::Deserialize<'de>,
     {
         let mut query_string = ::url::form_urlencoded::Serializer::new("".to_owned());
-        // raw_headers is for headers we don't know the proper type of (e.g. custom api key
-        // headers); headers is for ones we do know the type of.
-        let mut raw_headers = HashMap::new();
-        let mut headers: hyper::header::Headers = hyper::header::Headers::new();
 
         let mut path = self.path;
         for (k, v) in self.path_params {
@@ -116,46 +117,10 @@ impl Request {
             path = path.replace(&format!("{{{}}}", k), &v);
         }
 
-        for (k, v) in self.header_params {
-            raw_headers.insert(k, v);
-        }
-
         for (key, val) in self.query_params {
             query_string.append_pair(&key, &val);
         }
 
-        match self.auth {
-            Auth::ApiKey(apikey) => {
-                if let Some(ref key) = conf.api_key {
-                    let val = apikey.key(&key.prefix, &key.key);
-                    if apikey.in_query {
-                        query_string.append_pair(&apikey.param_name, &val);
-                    }
-                    if apikey.in_header {
-                        raw_headers.insert(apikey.param_name, val);
-                    }
-                }
-            }
-            Auth::Basic => {
-                if let Some(ref auth_conf) = conf.basic_auth {
-                    let auth = hyper::header::Authorization(hyper::header::Basic {
-                        username: auth_conf.0.to_owned(),
-                        password: auth_conf.1.to_owned(),
-                    });
-                    headers.set(auth);
-                }
-            }
-            Auth::Oauth => {
-                if let Some(ref token) = conf.oauth_access_token {
-                    let auth = hyper::header::Authorization(hyper::header::Bearer {
-                        token: token.to_owned(),
-                    });
-                    headers.set(auth);
-                }
-            }
-            Auth::None => {}
-        }
-
         let mut uri_str = format!("{}{}", conf.base_path, path);
 
         let query_string_str = query_string.finish();
@@ -164,76 +129,110 @@ impl Request {
             uri_str += &query_string_str;
         }
         let uri: hyper::Uri = match uri_str.parse() {
-            Err(e) => {
-                return Box::new(futures::future::err(Error::UriError(e)));
-            }
+            Err(e) => return Box::pin(futures::future::err(Error::UriError(e))),
             Ok(u) => u,
         };
 
-        let mut req = hyper::Request::new(self.method, uri);
-        {
-            let req_headers = req.headers_mut();
-            if let Some(ref user_agent) = conf.user_agent {
-                req_headers.set(UserAgent::new(Cow::Owned(user_agent.clone())));
-            }
+        let mut req_builder = hyper::Request::builder()
+            .uri(uri)
+            .method(self.method);
 
-            req_headers.extend(headers.iter());
-
-            for (key, val) in raw_headers {
-                req_headers.set_raw(key, val);
+        // Detect the authorization type if it hasn't been set.
+        let auth = self.auth.unwrap_or_else(||
+            if conf.api_key.is_some() {
+                panic!("Cannot automatically set the API key from the configuration, it must be specified in the OpenAPI definition")
+            } else if conf.oauth_access_token.is_some() {
+                Auth::Oauth
+            } else if conf.basic_auth.is_some() {
+                Auth::Basic
+            } else {
+                Auth::None
             }
+        );
+        match auth {
+            Auth::ApiKey(apikey) => {
+                if let Some(ref key) = conf.api_key {
+                    let val = apikey.key(&key.prefix, &key.key);
+                    if apikey.in_query {
+                        query_string.append_pair(&apikey.param_name, &val);
+                    }
+                    if apikey.in_header {
+                        req_builder = req_builder.header(&apikey.param_name, val);
+                    }
+                }
+            }
+            Auth::Basic => {
+                if let Some(ref auth_conf) = conf.basic_auth {
+                    let mut text = auth_conf.0.clone();
+                    text.push(':');
+                    if let Some(ref pass) = auth_conf.1 {
+                        text.push_str(&pass[..]);
+                    }
+                    let encoded = base64::encode(&text);
+                    req_builder = req_builder.header(AUTHORIZATION, encoded);
+                }
+            }
+            Auth::Oauth => {
+                if let Some(ref token) = conf.oauth_access_token {
+                    let text = "Bearer ".to_owned() + token;
+                    req_builder = req_builder.header(AUTHORIZATION, text);
+                }
+            }
+            Auth::None => {}
         }
 
-        if self.form_params.len() > 0 {
-            req.headers_mut().set(hyper::header::ContentType::form_url_encoded());
+        if let Some(ref user_agent) = conf.user_agent {
+            req_builder = req_builder.header(USER_AGENT, match HeaderValue::from_str(user_agent) {
+                Ok(header_value) => header_value,
+                Err(e) => return Box::pin(futures::future::err(super::Error::Header(e)))
+            });
+        }
+
+        for (k, v) in self.header_params {
+            req_builder = req_builder.header(&k, v);
+        }
+
+        let req_headers = req_builder.headers_mut().unwrap();
+        let request_result = if self.form_params.len() > 0 {
+            req_headers.insert(CONTENT_TYPE, HeaderValue::from_static("application/ x-www-form-urlencoded"));
             let mut enc = ::url::form_urlencoded::Serializer::new("".to_owned());
             for (k, v) in self.form_params {
                 enc.append_pair(&k, &v);
             }
-            req.set_body(enc.finish());
-        }
+            req_builder.body(hyper::Body::from(enc.finish()))
+        } else if let Some(body) = self.serialized_body {
+            req_headers.insert(CONTENT_TYPE, HeaderValue::from_static("application/json"));
+            req_headers.insert(CONTENT_LENGTH, body.len().into());
+            req_builder.body(hyper::Body::from(body))
+        } else {
+            req_builder.body(hyper::Body::default())
+        };
+        let request = match request_result {
+            Ok(request) => request,
+            Err(e) => return Box::pin(futures::future::err(Error::from(e)))
+        };
 
-        if let Some(body) = self.serialized_body {
-            req.headers_mut().set(hyper::header::ContentType::json());
-            req.headers_mut()
-                .set(hyper::header::ContentLength(body.len() as u64));
-            req.set_body(body);
-        }
-
-        let no_ret_type = self.no_return_type;
-        let res = conf.client
-                .request(req)
-                .map_err(|e| Error::from(e))
-                .and_then(|resp| {
-                    let status = resp.status();
-                    resp.body()
-                        .concat2()
-                        .and_then(move |body| Ok((status, body)))
-                        .map_err(|e| Error::from(e))
-                })
-                .and_then(|(status, body)| {
-                    if status.is_success() {
-                        Ok(body)
-                    } else {
-                        Err(Error::from((status, &*body)))
-                    }
-                });
-        Box::new(
-            res
-                .and_then(move |body| {
-                    let parsed: Result<U, _> = if no_ret_type {
-                        // This is a hack; if there's no_ret_type, U is (), but serde_json gives an
-                        // error when deserializing "" into (), so deserialize 'null' into it
-                        // instead.
-                        // An alternate option would be to require U: Default, and then return
-                        // U::default() here instead since () implements that, but then we'd
-                        // need to impl default for all models.
-                        serde_json::from_str("null")
-                    } else {
-                        serde_json::from_slice(&body)
-                    };
-                    parsed.map_err(|e| Error::from(e))
-                })
-        )
+        let no_return_type = self.no_return_type;
+        Box::pin(conf.client
+            .request(request)
+            .map_err(|e| Error::from(e))
+            .and_then(move |response| {
+                let status = response.status();
+                if !status.is_success() {
+                    futures::future::err::<U, Error>(Error::from((status, response.into_body()))).boxed()
+                } else if no_return_type {
+                    // This is a hack; if there's no_ret_type, U is (), but serde_json gives an
+                    // error when deserializing "" into (), so deserialize 'null' into it
+                    // instead.
+                    // An alternate option would be to require U: Default, and then return
+                    // U::default() here instead since () implements that, but then we'd
+                    // need to impl default for all models.
+                    futures::future::ok::<U, Error>(serde_json::from_str("null").expect("serde null value")).boxed()
+                } else {
+                    hyper::body::to_bytes(response.into_body())
+                        .map(|bytes| serde_json::from_slice(&bytes.unwrap()))
+                        .map_err(|e| Error::from(e)).boxed()
+                }
+            }))
     }
 }
diff --git a/samples/client/petstore/rust/hyper/petstore/src/apis/store_api.rs b/samples/client/petstore/rust/hyper/petstore/src/apis/store_api.rs
index 7e5aaa33da2..303a418d696 100644
--- a/samples/client/petstore/rust/hyper/petstore/src/apis/store_api.rs
+++ b/samples/client/petstore/rust/hyper/petstore/src/apis/store_api.rs
@@ -4,27 +4,29 @@
  * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
  *
  * The version of the OpenAPI document: 1.0.0
- * 
+ *
  * Generated by: https://openapi-generator.tech
  */
 
 use std::rc::Rc;
 use std::borrow::Borrow;
+use std::pin::Pin;
 #[allow(unused_imports)]
 use std::option::Option;
 
 use hyper;
-use serde_json;
 use futures::Future;
 
 use super::{Error, configuration};
 use super::request as __internal_request;
 
-pub struct StoreApiClient<C: hyper::client::Connect> {
+pub struct StoreApiClient<C: hyper::client::connect::Connect>
+    where C: Clone + std::marker::Send + Sync + 'static {
     configuration: Rc<configuration::Configuration<C>>,
 }
 
-impl<C: hyper::client::Connect> StoreApiClient<C> {
+impl<C: hyper::client::connect::Connect> StoreApiClient<C>
+    where C: Clone + std::marker::Send + Sync {
     pub fn new(configuration: Rc<configuration::Configuration<C>>) -> StoreApiClient<C> {
         StoreApiClient {
             configuration,
@@ -33,15 +35,17 @@ impl<C: hyper::client::Connect> StoreApiClient<C> {
 }
 
 pub trait StoreApi {
-    fn delete_order(&self, order_id: &str) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>>;
-    fn get_inventory(&self, ) -> Box<dyn Future<Item = ::std::collections::HashMap<String, i32>, Error = Error<serde_json::Value>>>;
-    fn get_order_by_id(&self, order_id: i64) -> Box<dyn Future<Item = crate::models::Order, Error = Error<serde_json::Value>>>;
-    fn place_order(&self, order: crate::models::Order) -> Box<dyn Future<Item = crate::models::Order, Error = Error<serde_json::Value>>>;
+    fn delete_order(&self, order_id: &str) -> Pin<Box<dyn Future<Output = Result<(), Error>>>>;
+    fn get_inventory(&self, ) -> Pin<Box<dyn Future<Output = Result<::std::collections::HashMap<String, i32>, Error>>>>;
+    fn get_order_by_id(&self, order_id: i64) -> Pin<Box<dyn Future<Output = Result<crate::models::Order, Error>>>>;
+    fn place_order(&self, body: crate::models::Order) -> Pin<Box<dyn Future<Output = Result<crate::models::Order, Error>>>>;
 }
 
-impl<C: hyper::client::Connect>StoreApi for StoreApiClient<C> {
-    fn delete_order(&self, order_id: &str) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Delete, "/store/order/{orderId}".to_string())
+impl<C: hyper::client::connect::Connect>StoreApi for StoreApiClient<C>
+    where C: Clone + std::marker::Send + Sync {
+    #[allow(unused_mut)]
+    fn delete_order(&self, order_id: &str) -> Pin<Box<dyn Future<Output = Result<(), Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::DELETE, "/store/order/{orderId}".to_string())
         ;
         req = req.with_path_param("orderId".to_string(), order_id.to_string());
         req = req.returns_nothing();
@@ -49,8 +53,9 @@ impl<C: hyper::client::Connect>StoreApi for StoreApiClient<C> {
         req.execute(self.configuration.borrow())
     }
 
-    fn get_inventory(&self, ) -> Box<dyn Future<Item = ::std::collections::HashMap<String, i32>, Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Get, "/store/inventory".to_string())
+    #[allow(unused_mut)]
+    fn get_inventory(&self, ) -> Pin<Box<dyn Future<Output = Result<::std::collections::HashMap<String, i32>, Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::GET, "/store/inventory".to_string())
             .with_auth(__internal_request::Auth::ApiKey(__internal_request::ApiKey{
                 in_header: true,
                 in_query: false,
@@ -61,16 +66,18 @@ impl<C: hyper::client::Connect>StoreApi for StoreApiClient<C> {
         req.execute(self.configuration.borrow())
     }
 
-    fn get_order_by_id(&self, order_id: i64) -> Box<dyn Future<Item = crate::models::Order, Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Get, "/store/order/{orderId}".to_string())
+    #[allow(unused_mut)]
+    fn get_order_by_id(&self, order_id: i64) -> Pin<Box<dyn Future<Output = Result<crate::models::Order, Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::GET, "/store/order/{orderId}".to_string())
         ;
         req = req.with_path_param("orderId".to_string(), order_id.to_string());
 
         req.execute(self.configuration.borrow())
     }
 
-    fn place_order(&self, order: crate::models::Order) -> Box<dyn Future<Item = crate::models::Order, Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Post, "/store/order".to_string())
+    #[allow(unused_mut)]
+    fn place_order(&self, body: crate::models::Order) -> Pin<Box<dyn Future<Output = Result<crate::models::Order, Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::POST, "/store/order".to_string())
         ;
         req = req.with_body_param(order);
 
diff --git a/samples/client/petstore/rust/hyper/petstore/src/apis/user_api.rs b/samples/client/petstore/rust/hyper/petstore/src/apis/user_api.rs
index e7326d05c4d..2651e807362 100644
--- a/samples/client/petstore/rust/hyper/petstore/src/apis/user_api.rs
+++ b/samples/client/petstore/rust/hyper/petstore/src/apis/user_api.rs
@@ -4,27 +4,29 @@
  * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
  *
  * The version of the OpenAPI document: 1.0.0
- * 
+ *
  * Generated by: https://openapi-generator.tech
  */
 
 use std::rc::Rc;
 use std::borrow::Borrow;
+use std::pin::Pin;
 #[allow(unused_imports)]
 use std::option::Option;
 
 use hyper;
-use serde_json;
 use futures::Future;
 
 use super::{Error, configuration};
 use super::request as __internal_request;
 
-pub struct UserApiClient<C: hyper::client::Connect> {
+pub struct UserApiClient<C: hyper::client::connect::Connect>
+    where C: Clone + std::marker::Send + Sync + 'static {
     configuration: Rc<configuration::Configuration<C>>,
 }
 
-impl<C: hyper::client::Connect> UserApiClient<C> {
+impl<C: hyper::client::connect::Connect> UserApiClient<C>
+    where C: Clone + std::marker::Send + Sync {
     pub fn new(configuration: Rc<configuration::Configuration<C>>) -> UserApiClient<C> {
         UserApiClient {
             configuration,
@@ -33,24 +35,21 @@ impl<C: hyper::client::Connect> UserApiClient<C> {
 }
 
 pub trait UserApi {
-    fn create_user(&self, user: crate::models::User) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>>;
-    fn create_users_with_array_input(&self, user: Vec<crate::models::User>) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>>;
-    fn create_users_with_list_input(&self, user: Vec<crate::models::User>) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>>;
-    fn delete_user(&self, username: &str) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>>;
-    fn get_user_by_name(&self, username: &str) -> Box<dyn Future<Item = crate::models::User, Error = Error<serde_json::Value>>>;
-    fn login_user(&self, username: &str, password: &str) -> Box<dyn Future<Item = String, Error = Error<serde_json::Value>>>;
-    fn logout_user(&self, ) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>>;
-    fn update_user(&self, username: &str, user: crate::models::User) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>>;
+    fn create_user(&self, body: crate::models::User) -> Pin<Box<dyn Future<Output = Result<(), Error>>>>;
+    fn create_users_with_array_input(&self, body: Vec<crate::models::User>) -> Pin<Box<dyn Future<Output = Result<(), Error>>>>;
+    fn create_users_with_list_input(&self, body: Vec<crate::models::User>) -> Pin<Box<dyn Future<Output = Result<(), Error>>>>;
+    fn delete_user(&self, username: &str) -> Pin<Box<dyn Future<Output = Result<(), Error>>>>;
+    fn get_user_by_name(&self, username: &str) -> Pin<Box<dyn Future<Output = Result<crate::models::User, Error>>>>;
+    fn login_user(&self, username: &str, password: &str) -> Pin<Box<dyn Future<Output = Result<String, Error>>>>;
+    fn logout_user(&self, ) -> Pin<Box<dyn Future<Output = Result<(), Error>>>>;
+    fn update_user(&self, username: &str, body: crate::models::User) -> Pin<Box<dyn Future<Output = Result<(), Error>>>>;
 }
 
-impl<C: hyper::client::Connect>UserApi for UserApiClient<C> {
-    fn create_user(&self, user: crate::models::User) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Post, "/user".to_string())
-            .with_auth(__internal_request::Auth::ApiKey(__internal_request::ApiKey{
-                in_header: true,
-                in_query: false,
-                param_name: "api_key".to_owned(),
-            }))
+impl<C: hyper::client::connect::Connect>UserApi for UserApiClient<C>
+    where C: Clone + std::marker::Send + Sync {
+    #[allow(unused_mut)]
+    fn create_user(&self, body: crate::models::User) -> Pin<Box<dyn Future<Output = Result<(), Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::POST, "/user".to_string())
         ;
         req = req.with_body_param(user);
         req = req.returns_nothing();
@@ -58,13 +57,9 @@ impl<C: hyper::client::Connect>UserApi for UserApiClient<C> {
         req.execute(self.configuration.borrow())
     }
 
-    fn create_users_with_array_input(&self, user: Vec<crate::models::User>) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Post, "/user/createWithArray".to_string())
-            .with_auth(__internal_request::Auth::ApiKey(__internal_request::ApiKey{
-                in_header: true,
-                in_query: false,
-                param_name: "api_key".to_owned(),
-            }))
+    #[allow(unused_mut)]
+    fn create_users_with_array_input(&self, body: Vec<crate::models::User>) -> Pin<Box<dyn Future<Output = Result<(), Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::POST, "/user/createWithArray".to_string())
         ;
         req = req.with_body_param(user);
         req = req.returns_nothing();
@@ -72,13 +67,9 @@ impl<C: hyper::client::Connect>UserApi for UserApiClient<C> {
         req.execute(self.configuration.borrow())
     }
 
-    fn create_users_with_list_input(&self, user: Vec<crate::models::User>) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Post, "/user/createWithList".to_string())
-            .with_auth(__internal_request::Auth::ApiKey(__internal_request::ApiKey{
-                in_header: true,
-                in_query: false,
-                param_name: "api_key".to_owned(),
-            }))
+    #[allow(unused_mut)]
+    fn create_users_with_list_input(&self, body: Vec<crate::models::User>) -> Pin<Box<dyn Future<Output = Result<(), Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::POST, "/user/createWithList".to_string())
         ;
         req = req.with_body_param(user);
         req = req.returns_nothing();
@@ -86,13 +77,9 @@ impl<C: hyper::client::Connect>UserApi for UserApiClient<C> {
         req.execute(self.configuration.borrow())
     }
 
-    fn delete_user(&self, username: &str) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Delete, "/user/{username}".to_string())
-            .with_auth(__internal_request::Auth::ApiKey(__internal_request::ApiKey{
-                in_header: true,
-                in_query: false,
-                param_name: "api_key".to_owned(),
-            }))
+    #[allow(unused_mut)]
+    fn delete_user(&self, username: &str) -> Pin<Box<dyn Future<Output = Result<(), Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::DELETE, "/user/{username}".to_string())
         ;
         req = req.with_path_param("username".to_string(), username.to_string());
         req = req.returns_nothing();
@@ -100,16 +87,18 @@ impl<C: hyper::client::Connect>UserApi for UserApiClient<C> {
         req.execute(self.configuration.borrow())
     }
 
-    fn get_user_by_name(&self, username: &str) -> Box<dyn Future<Item = crate::models::User, Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Get, "/user/{username}".to_string())
+    #[allow(unused_mut)]
+    fn get_user_by_name(&self, username: &str) -> Pin<Box<dyn Future<Output = Result<crate::models::User, Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::GET, "/user/{username}".to_string())
         ;
         req = req.with_path_param("username".to_string(), username.to_string());
 
         req.execute(self.configuration.borrow())
     }
 
-    fn login_user(&self, username: &str, password: &str) -> Box<dyn Future<Item = String, Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Get, "/user/login".to_string())
+    #[allow(unused_mut)]
+    fn login_user(&self, username: &str, password: &str) -> Pin<Box<dyn Future<Output = Result<String, Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::GET, "/user/login".to_string())
         ;
         req = req.with_query_param("username".to_string(), username.to_string());
         req = req.with_query_param("password".to_string(), password.to_string());
@@ -117,26 +106,18 @@ impl<C: hyper::client::Connect>UserApi for UserApiClient<C> {
         req.execute(self.configuration.borrow())
     }
 
-    fn logout_user(&self, ) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Get, "/user/logout".to_string())
-            .with_auth(__internal_request::Auth::ApiKey(__internal_request::ApiKey{
-                in_header: true,
-                in_query: false,
-                param_name: "api_key".to_owned(),
-            }))
+    #[allow(unused_mut)]
+    fn logout_user(&self, ) -> Pin<Box<dyn Future<Output = Result<(), Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::GET, "/user/logout".to_string())
         ;
         req = req.returns_nothing();
 
         req.execute(self.configuration.borrow())
     }
 
-    fn update_user(&self, username: &str, user: crate::models::User) -> Box<dyn Future<Item = (), Error = Error<serde_json::Value>>> {
-        let mut req = __internal_request::Request::new(hyper::Method::Put, "/user/{username}".to_string())
-            .with_auth(__internal_request::Auth::ApiKey(__internal_request::ApiKey{
-                in_header: true,
-                in_query: false,
-                param_name: "api_key".to_owned(),
-            }))
+    #[allow(unused_mut)]
+    fn update_user(&self, username: &str, body: crate::models::User) -> Pin<Box<dyn Future<Output = Result<(), Error>>>> {
+        let mut req = __internal_request::Request::new(hyper::Method::PUT, "/user/{username}".to_string())
         ;
         req = req.with_path_param("username".to_string(), username.to_string());
         req = req.with_body_param(user);