diff --git a/modules/openapi-generator/src/main/resources/r/NAMESPACE.mustache b/modules/openapi-generator/src/main/resources/r/NAMESPACE.mustache
index b040f5adc44..720eb69bdab 100644
--- a/modules/openapi-generator/src/main/resources/r/NAMESPACE.mustache
+++ b/modules/openapi-generator/src/main/resources/r/NAMESPACE.mustache
@@ -5,6 +5,7 @@ import(R6)
 import(jsonlite)
 import(httr)
 import(base64enc)
+import(stringr)
 
 # Core
 export(ApiClient)
diff --git a/modules/openapi-generator/src/main/resources/r/api.mustache b/modules/openapi-generator/src/main/resources/r/api.mustache
index 54fa845382e..cfcab5359b2 100644
--- a/modules/openapi-generator/src/main/resources/r/api.mustache
+++ b/modules/openapi-generator/src/main/resources/r/api.mustache
@@ -333,10 +333,18 @@
       {{/isOAuth}}
       {{/authMethods}}
 
+      # The Accept request HTTP header
+      accepts = list({{#produces}}"{{{mediaType}}}"{{^-last}}, {{/-last}}{{/produces}})
+
+      # The Content-Type representation header
+      content_types = list({{#consumes}}"{{{mediaType}}}"{{^-last}}, {{/-last}}{{/consumes}})
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "{{httpMethod}}",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  {{#vendorExtensions.x-streaming}}
                                  stream_callback = stream_callback,
diff --git a/modules/openapi-generator/src/main/resources/r/api_client.mustache b/modules/openapi-generator/src/main/resources/r/api_client.mustache
index a581d4af6b3..8e78e508898 100644
--- a/modules/openapi-generator/src/main/resources/r/api_client.mustache
+++ b/modules/openapi-generator/src/main/resources/r/api_client.mustache
@@ -133,14 +133,18 @@ ApiClient  <- R6::R6Class(
     #' @param method HTTP method.
     #' @param query_params The query parameters.
     #' @param header_params The header parameters.
+    #' @param accepts The list of Accept headers.
+    #' @param content_types The list of Content-Type headers.
     #' @param body The HTTP request body.
     #' @param stream_callback Callback function to process the data stream
     #' @param ... Other optional arguments.
     #' @return HTTP response
     #' @export
-    CallApi = function(url, method, query_params, header_params, body, stream_callback = NULL, ...) {
+    CallApi = function(url, method, query_params, header_params, accepts, content_types,
+                       body, stream_callback = NULL, ...) {
 
-      resp <- self$Execute(url, method, query_params, header_params, body, stream_callback = stream_callback, ...)
+      resp <- self$Execute(url, method, query_params, header_params, accepts, content_types,
+                           body, stream_callback = stream_callback, ...)
       status_code <- httr::status_code(resp)
 
       if (is.null(self$max_retry_attempts)) {
@@ -171,12 +175,15 @@ ApiClient  <- R6::R6Class(
     #' @param method HTTP method.
     #' @param query_params The query parameters.
     #' @param header_params The header parameters.
+    #' @param accepts The list of Accept headers
+    #' @param content_types The list of Content-Type headers
     #' @param body The HTTP request body.
     #' @param stream_callback Callback function to process data stream
     #' @param ... Other optional arguments.
     #' @return HTTP response
     #' @export
-    Execute = function(url, method, query_params, header_params, body, stream_callback = NULL, ...) {
+    Execute = function(url, method, query_params, header_params, accepts, content_types,
+                       body, stream_callback = NULL, ...) {
       headers <- httr::add_headers(c(header_params, self$default_headers))
 
       {{! Adding timeout that can be set at the apiClient object level}}
@@ -185,6 +192,18 @@ ApiClient  <- R6::R6Class(
         http_timeout <- httr::timeout(self$timeout)
       }
 
+      # set HTTP accept header
+      accept = self$select_header(accepts)
+      if (!is.null(accept)) {
+        headers['Accept'] = accept
+      }
+
+      # set HTTP content-type header
+      content_type = self$select_header(content_types)
+      if (!is.null(content_type)) {
+        headers['Content-Type'] = content_type
+      }
+
       if (method == "GET") {
         if (typeof(stream_callback) == "closure") {
           httr::GET(url, query = query_params, headers, http_timeout,
@@ -265,7 +284,6 @@ ApiClient  <- R6::R6Class(
       resp_obj <- jsonlite::fromJSON(httr::content(resp, "text", encoding = "UTF-8"))
       self$deserializeObj(resp_obj, return_type, pkg_env)
     },
-
     #' Deserialize the response from jsonlite object based on the given type
     #'
     #' @description
@@ -324,6 +342,31 @@ ApiClient  <- R6::R6Class(
         return_obj <- obj
       }
       return_obj
+    },
+    #' Return a propery header (for accept or content-type). If JSON-related MIME is found,
+    #' return it. Otherwise, return the first one, if any.
+    #'
+    #' @description
+    #' Return a propery header (for accept or content-type). If JSON-related MIME is found,
+    #' return it. Otherwise, return the first one, if any.
+    #'
+    #' @param headers A list of headers
+    #' @return A header (e.g. 'application/json')
+    #' @export
+    select_header = function(headers) {
+      if (length(headers) == 0) {
+        return(invisible(NULL))
+      } else {
+        for (header in headers) {
+          if (str_detect(header, "(?i)^(application/json|[^;/ \t]+/[^;/ \t]+[+]json)[ \t]*(;.*)?$")) {
+            # return JSON-related MIME
+            return(header)
+          }
+        }
+
+        # not json mime type, simply return the first one
+        return(headers[1])
+      }
     }
   )
 )
diff --git a/modules/openapi-generator/src/main/resources/r/description.mustache b/modules/openapi-generator/src/main/resources/r/description.mustache
index 2a16f842bf1..7187fef5b5c 100644
--- a/modules/openapi-generator/src/main/resources/r/description.mustache
+++ b/modules/openapi-generator/src/main/resources/r/description.mustache
@@ -11,5 +11,5 @@ Encoding: UTF-8
 License: {{#lambdaLicense}}{{licenseInfo}}{{/lambdaLicense}}{{^licenseInfo}}Unlicense{{/licenseInfo}}
 LazyData: true
 Suggests: testthat
-Imports: jsonlite, httr, R6, base64enc
+Imports: jsonlite, httr, R6, base64enc, stringr
 RoxygenNote: 7.2.0
diff --git a/samples/client/petstore/R/DESCRIPTION b/samples/client/petstore/R/DESCRIPTION
index 2afb45624b0..d8e1a4dfcde 100644
--- a/samples/client/petstore/R/DESCRIPTION
+++ b/samples/client/petstore/R/DESCRIPTION
@@ -11,5 +11,5 @@ Encoding: UTF-8
 License: Apache License 2.0
 LazyData: true
 Suggests: testthat
-Imports: jsonlite, httr, R6, base64enc
+Imports: jsonlite, httr, R6, base64enc, stringr
 RoxygenNote: 7.2.0
diff --git a/samples/client/petstore/R/NAMESPACE b/samples/client/petstore/R/NAMESPACE
index d8fc867efa7..667ff45b7bf 100644
--- a/samples/client/petstore/R/NAMESPACE
+++ b/samples/client/petstore/R/NAMESPACE
@@ -5,6 +5,7 @@ import(R6)
 import(jsonlite)
 import(httr)
 import(base64enc)
+import(stringr)
 
 # Core
 export(ApiClient)
diff --git a/samples/client/petstore/R/R/api_client.R b/samples/client/petstore/R/R/api_client.R
index ae2cd498a9c..77ed87bd912 100644
--- a/samples/client/petstore/R/R/api_client.R
+++ b/samples/client/petstore/R/R/api_client.R
@@ -138,14 +138,18 @@ ApiClient  <- R6::R6Class(
     #' @param method HTTP method.
     #' @param query_params The query parameters.
     #' @param header_params The header parameters.
+    #' @param accepts The list of Accept headers.
+    #' @param content_types The list of Content-Type headers.
     #' @param body The HTTP request body.
     #' @param stream_callback Callback function to process the data stream
     #' @param ... Other optional arguments.
     #' @return HTTP response
     #' @export
-    CallApi = function(url, method, query_params, header_params, body, stream_callback = NULL, ...) {
+    CallApi = function(url, method, query_params, header_params, accepts, content_types,
+                       body, stream_callback = NULL, ...) {
 
-      resp <- self$Execute(url, method, query_params, header_params, body, stream_callback = stream_callback, ...)
+      resp <- self$Execute(url, method, query_params, header_params, accepts, content_types,
+                           body, stream_callback = stream_callback, ...)
       status_code <- httr::status_code(resp)
 
       if (is.null(self$max_retry_attempts)) {
@@ -176,12 +180,15 @@ ApiClient  <- R6::R6Class(
     #' @param method HTTP method.
     #' @param query_params The query parameters.
     #' @param header_params The header parameters.
+    #' @param accepts The list of Accept headers
+    #' @param content_types The list of Content-Type headers
     #' @param body The HTTP request body.
     #' @param stream_callback Callback function to process data stream
     #' @param ... Other optional arguments.
     #' @return HTTP response
     #' @export
-    Execute = function(url, method, query_params, header_params, body, stream_callback = NULL, ...) {
+    Execute = function(url, method, query_params, header_params, accepts, content_types,
+                       body, stream_callback = NULL, ...) {
       headers <- httr::add_headers(c(header_params, self$default_headers))
 
       http_timeout <- NULL
@@ -189,6 +196,18 @@ ApiClient  <- R6::R6Class(
         http_timeout <- httr::timeout(self$timeout)
       }
 
+      # set HTTP accept header
+      accept = self$select_header(accepts)
+      if (!is.null(accept)) {
+        headers['Accept'] = accept
+      }
+
+      # set HTTP content-type header
+      content_type = self$select_header(content_types)
+      if (!is.null(content_type)) {
+        headers['Content-Type'] = content_type
+      }
+
       if (method == "GET") {
         if (typeof(stream_callback) == "closure") {
           httr::GET(url, query = query_params, headers, http_timeout,
@@ -264,7 +283,6 @@ ApiClient  <- R6::R6Class(
       resp_obj <- jsonlite::fromJSON(httr::content(resp, "text", encoding = "UTF-8"))
       self$deserializeObj(resp_obj, return_type, pkg_env)
     },
-
     #' Deserialize the response from jsonlite object based on the given type
     #'
     #' @description
@@ -323,6 +341,31 @@ ApiClient  <- R6::R6Class(
         return_obj <- obj
       }
       return_obj
+    },
+    #' Return a propery header (for accept or content-type). If JSON-related MIME is found,
+    #' return it. Otherwise, return the first one, if any.
+    #'
+    #' @description
+    #' Return a propery header (for accept or content-type). If JSON-related MIME is found,
+    #' return it. Otherwise, return the first one, if any.
+    #'
+    #' @param headers A list of headers
+    #' @return A header (e.g. 'application/json')
+    #' @export
+    select_header = function(headers) {
+      if (length(headers) == 0) {
+        return(invisible(NULL))
+      } else {
+        for (header in headers) {
+          if (str_detect(header, "(?i)^(application/json|[^;/ \t]+/[^;/ \t]+[+]json)[ \t]*(;.*)?$")) {
+            # return JSON-related MIME
+            return(header)
+          }
+        }
+
+        # not json mime type, simply return the first one
+        return(headers[1])
+      }
     }
   )
 )
diff --git a/samples/client/petstore/R/R/fake_api.R b/samples/client/petstore/R/R/fake_api.R
index 250b0a822d4..fe1ae74cf00 100644
--- a/samples/client/petstore/R/R/fake_api.R
+++ b/samples/client/petstore/R/R/fake_api.R
@@ -137,10 +137,18 @@ FakeApi <- R6::R6Class(
       body <- NULL
       url_path <- "/fake/data_file"
 
+      # The Accept request HTTP header
+      accepts = list("application/xml", "application/json")
+
+      # The Content-Type representation header
+      content_types = list()
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "GET",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
diff --git a/samples/client/petstore/R/R/pet_api.R b/samples/client/petstore/R/R/pet_api.R
index 707283312ac..fa60b70ad2d 100644
--- a/samples/client/petstore/R/R/pet_api.R
+++ b/samples/client/petstore/R/R/pet_api.R
@@ -588,10 +588,18 @@ PetApi <- R6::R6Class(
       # HTTP basic auth
       header_params["Authorization"] <- paste("Basic", base64enc::base64encode(charToRaw(paste(self$api_client$username, self$api_client$password, sep = ":"))))
 
+      # The Accept request HTTP header
+      accepts = list("application/xml", "application/json")
+
+      # The Content-Type representation header
+      content_types = list("application/json", "application/xml", "multipart/related")
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "POST",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -690,10 +698,18 @@ PetApi <- R6::R6Class(
       # OAuth token
       header_params["Authorization"] <- paste("Bearer", self$api_client$access_token, sep = " ")
 
+      # The Accept request HTTP header
+      accepts = list()
+
+      # The Content-Type representation header
+      content_types = list()
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "DELETE",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -775,10 +791,18 @@ PetApi <- R6::R6Class(
       # OAuth token
       header_params["Authorization"] <- paste("Bearer", self$api_client$access_token, sep = " ")
 
+      # The Accept request HTTP header
+      accepts = list("application/xml", "application/json")
+
+      # The Content-Type representation header
+      content_types = list()
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "GET",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -873,10 +897,18 @@ PetApi <- R6::R6Class(
       # OAuth token
       header_params["Authorization"] <- paste("Bearer", self$api_client$access_token, sep = " ")
 
+      # The Accept request HTTP header
+      accepts = list("application/xml", "application/json")
+
+      # The Content-Type representation header
+      content_types = list()
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "GET",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -974,10 +1006,18 @@ PetApi <- R6::R6Class(
 
       header_params["Authorization"] <- paste("Bearer", self$api_client$bearer_token, sep = " ")
 
+      # The Accept request HTTP header
+      accepts = list("application/xml", "application/json")
+
+      # The Content-Type representation header
+      content_types = list()
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "GET",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -1084,10 +1124,18 @@ PetApi <- R6::R6Class(
         header_params["api_key"] <- paste(unlist(self$api_client$api_keys["api_key"]), collapse = "")
       }
 
+      # The Accept request HTTP header
+      accepts = list("application/xml", "application/json")
+
+      # The Content-Type representation header
+      content_types = list()
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "GET",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  stream_callback = stream_callback,
                                  ...)
@@ -1192,10 +1240,18 @@ PetApi <- R6::R6Class(
       # OAuth token
       header_params["Authorization"] <- paste("Bearer", self$api_client$access_token, sep = " ")
 
+      # The Accept request HTTP header
+      accepts = list("application/xml", "application/json")
+
+      # The Content-Type representation header
+      content_types = list("application/json", "application/xml", "multipart/related")
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "PUT",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -1300,10 +1356,18 @@ PetApi <- R6::R6Class(
       # OAuth token
       header_params["Authorization"] <- paste("Bearer", self$api_client$access_token, sep = " ")
 
+      # The Accept request HTTP header
+      accepts = list()
+
+      # The Content-Type representation header
+      content_types = list("application/x-www-form-urlencoded")
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "POST",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -1397,10 +1461,18 @@ PetApi <- R6::R6Class(
       # OAuth token
       header_params["Authorization"] <- paste("Bearer", self$api_client$access_token, sep = " ")
 
+      # The Accept request HTTP header
+      accepts = list("application/json")
+
+      # The Content-Type representation header
+      content_types = list("multipart/form-data")
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "POST",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
diff --git a/samples/client/petstore/R/R/store_api.R b/samples/client/petstore/R/R/store_api.R
index 9ce83ad4e4f..41c63c796a7 100644
--- a/samples/client/petstore/R/R/store_api.R
+++ b/samples/client/petstore/R/R/store_api.R
@@ -289,10 +289,18 @@ StoreApi <- R6::R6Class(
       }
 
 
+      # The Accept request HTTP header
+      accepts = list()
+
+      # The Content-Type representation header
+      content_types = list()
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "DELETE",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -367,10 +375,18 @@ StoreApi <- R6::R6Class(
         header_params["api_key"] <- paste(unlist(self$api_client$api_keys["api_key"]), collapse = "")
       }
 
+      # The Accept request HTTP header
+      accepts = list("application/json")
+
+      # The Content-Type representation header
+      content_types = list()
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "GET",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -467,10 +483,18 @@ StoreApi <- R6::R6Class(
       }
 
 
+      # The Accept request HTTP header
+      accepts = list("application/xml", "application/json")
+
+      # The Content-Type representation header
+      content_types = list()
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "GET",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -568,10 +592,18 @@ StoreApi <- R6::R6Class(
 
       url_path <- "/store/order"
 
+      # The Accept request HTTP header
+      accepts = list("application/xml", "application/json")
+
+      # The Content-Type representation header
+      content_types = list("application/json")
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "POST",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
diff --git a/samples/client/petstore/R/R/user_api.R b/samples/client/petstore/R/R/user_api.R
index 07dbd47a307..8c0bc7080ff 100644
--- a/samples/client/petstore/R/R/user_api.R
+++ b/samples/client/petstore/R/R/user_api.R
@@ -480,10 +480,18 @@ UserApi <- R6::R6Class(
         header_params["api_key"] <- paste(unlist(self$api_client$api_keys["api_key"]), collapse = "")
       }
 
+      # The Accept request HTTP header
+      accepts = list()
+
+      # The Content-Type representation header
+      content_types = list("application/json")
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "POST",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -573,10 +581,18 @@ UserApi <- R6::R6Class(
         header_params["api_key"] <- paste(unlist(self$api_client$api_keys["api_key"]), collapse = "")
       }
 
+      # The Accept request HTTP header
+      accepts = list()
+
+      # The Content-Type representation header
+      content_types = list("application/json")
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "POST",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -666,10 +682,18 @@ UserApi <- R6::R6Class(
         header_params["api_key"] <- paste(unlist(self$api_client$api_keys["api_key"]), collapse = "")
       }
 
+      # The Accept request HTTP header
+      accepts = list()
+
+      # The Content-Type representation header
+      content_types = list("application/json")
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "POST",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -755,10 +779,18 @@ UserApi <- R6::R6Class(
         header_params["api_key"] <- paste(unlist(self$api_client$api_keys["api_key"]), collapse = "")
       }
 
+      # The Accept request HTTP header
+      accepts = list()
+
+      # The Content-Type representation header
+      content_types = list()
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "DELETE",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -842,10 +874,18 @@ UserApi <- R6::R6Class(
       }
 
 
+      # The Accept request HTTP header
+      accepts = list("application/xml", "application/json")
+
+      # The Content-Type representation header
+      content_types = list()
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "GET",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -947,10 +987,18 @@ UserApi <- R6::R6Class(
       body <- NULL
       url_path <- "/user/login"
 
+      # The Accept request HTTP header
+      accepts = list("application/xml", "application/json")
+
+      # The Content-Type representation header
+      content_types = list()
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "GET",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -1036,10 +1084,18 @@ UserApi <- R6::R6Class(
         header_params["api_key"] <- paste(unlist(self$api_client$api_keys["api_key"]), collapse = "")
       }
 
+      # The Accept request HTTP header
+      accepts = list()
+
+      # The Content-Type representation header
+      content_types = list()
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "GET",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
@@ -1139,10 +1195,18 @@ UserApi <- R6::R6Class(
         header_params["api_key"] <- paste(unlist(self$api_client$api_keys["api_key"]), collapse = "")
       }
 
+      # The Accept request HTTP header
+      accepts = list()
+
+      # The Content-Type representation header
+      content_types = list("application/json")
+
       resp <- self$api_client$CallApi(url = paste0(self$api_client$base_path, url_path),
                                  method = "PUT",
                                  query_params = query_params,
                                  header_params = header_params,
+                                 accepts = accepts,
+                                 content_types = content_types,
                                  body = body,
                                  ...)
 
diff --git a/samples/client/petstore/R/build_and_test.bash b/samples/client/petstore/R/build_and_test.bash
index 2079f75da03..0e7828ec879 100644
--- a/samples/client/petstore/R/build_and_test.bash
+++ b/samples/client/petstore/R/build_and_test.bash
@@ -18,6 +18,7 @@ Rscript -e "install.packages('base64enc', repos='$REPO', lib='$R_LIBS_USER')"
 Rscript -e "install.packages('rlang', repos='$REPO', lib='$R_LIBS_USER')"
 Rscript -e "install.packages('rjson', repos='$REPO', lib='$R_LIBS_USER')"
 Rscript -e "install.packages('devtools', repos='$REPO', lib='$R_LIBS_USER')"
+Rscript -e "install.packages('stringr', repos='$REPO', lib='$R_LIBS_USER')"
 
 rm petstore_1.0.0.tar.gz || true