Support deprecated API endpoints in reqwest-based Rust clients

Previously, if an API endpoint was marked deprecated, this fact was not
reflected in the generated Rust clients using the reqwest library. We
want to know exactly when our client code is using a deprecated endpoint,
so marking the corresponding functions with the `#[deprecatd]` attribute
would be very helpful. Uses of the endpoint would then be picked up by
linters so that we can react.

This adds a line to the template which marks functions generated from
deprecated endpoints with the `#[deprecated]` attribute.

This does not touch any of the other client generators for Rust or any
other language, since they are out of scope for our needs.

Unfortunately, even after about a dozen attempts, I was unable to coax
Mustache into not introducing an extra vertical whitespace when the
`#[deprecated]` attribute is absent. This has no effect on functionality
of the generated code, but is visually unappealing.

Author: Bradford Hovinen

modules/openapi-generator/src/main/resources/rust/reqwest/api.mustache

@@ -99,6 +99,7 @@ pub enum {{{operationIdCamelCase}}}Error {
 {{#notes}}
 /// {{{.}}}
 {{/notes}}
+{{#isDeprecated}}#[deprecated]{{/isDeprecated}}
 {{#vendorExtensions.x-group-parameters}}
 pub {{#supportAsync}}async {{/supportAsync}}fn {{{operationId}}}(configuration: &configuration::Configuration{{#allParams}}{{#-first}}, {{!
 ### Params

samples/client/others/rust/reqwest-regression-16119/src/apis/default_api.rs

@@ -23,6 +23,7 @@ pub enum ReproError {
 }
 
 
+
 pub fn repro(configuration: &configuration::Configuration, ) -> Result<models::Parent, Error<ReproError>> {
 
     let uri_str = format!("{}/repro", configuration.base_path);

samples/client/others/rust/reqwest/api-with-ref-param/src/apis/default_api.rs

@@ -23,6 +23,7 @@ pub enum DemoColorGetError {
 }
 
 
+
 pub async fn demo_color_get(configuration: &configuration::Configuration, color: models::Color) -> Result<(), Error<DemoColorGetError>> {
     // add a prefix to parameters to efficiently prevent name collisions
     let p_path_color = color;

samples/client/others/rust/reqwest/composed-oneof/src/apis/default_api.rs

@@ -30,6 +30,7 @@ pub enum GetStateError {
 }
 
 
+
 pub fn create_state(configuration: &configuration::Configuration, create_state_request: models::CreateStateRequest) -> Result<(), Error<CreateStateError>> {
     // add a prefix to parameters to efficiently prevent name collisions
     let p_body_create_state_request = create_state_request;
@@ -56,6 +57,7 @@ pub fn create_state(configuration: &configuration::Configuration, create_state_r
     }
 }
 
+
 pub fn get_state(configuration: &configuration::Configuration, ) -> Result<models::GetState200Response, Error<GetStateError>> {
 
     let uri_str = format!("{}/state", configuration.base_path);

samples/client/others/rust/reqwest/emptyObject/src/apis/default_api.rs

@@ -23,6 +23,7 @@ pub enum EndpointGetError {
 }
 
 
+
 pub fn endpoint_get(configuration: &configuration::Configuration, ) -> Result<models::EmptyObject, Error<EndpointGetError>> {
 
     let uri_str = format!("{}/endpoint", configuration.base_path);

samples/client/others/rust/reqwest/oneOf-array-map/src/apis/default_api.rs

@@ -30,6 +30,7 @@ pub enum TestError {
 }
 
 
+
 pub fn root_get(configuration: &configuration::Configuration, ) -> Result<models::Fruit, Error<RootGetError>> {
 
     let uri_str = format!("{}/", configuration.base_path);
@@ -64,6 +65,7 @@ pub fn root_get(configuration: &configuration::Configuration, ) -> Result<models
     }
 }
 
+
 pub fn test(configuration: &configuration::Configuration, body: Option<serde_json::Value>) -> Result<(), Error<TestError>> {
     // add a prefix to parameters to efficiently prevent name collisions
     let p_body_body = body;

samples/client/others/rust/reqwest/oneOf-reuseRef/src/apis/default_api.rs

@@ -23,6 +23,7 @@ pub enum GetFruitError {
 }
 
 
+
 pub fn get_fruit(configuration: &configuration::Configuration, ) -> Result<models::Fruit, Error<GetFruitError>> {
 
     let uri_str = format!("{}/example", configuration.base_path);

samples/client/others/rust/reqwest/oneOf/src/apis/bar_api.rs

@@ -23,6 +23,7 @@ pub enum CreateBarError {
 }
 
 
+
 pub fn create_bar(configuration: &configuration::Configuration, bar_create: models::BarCreate) -> Result<models::Bar, Error<CreateBarError>> {
     // add a prefix to parameters to efficiently prevent name collisions
     let p_body_bar_create = bar_create;

samples/client/others/rust/reqwest/oneOf/src/apis/foo_api.rs

@@ -30,6 +30,7 @@ pub enum GetAllFoosError {
 }
 
 
+
 pub fn create_foo(configuration: &configuration::Configuration, foo: Option<models::Foo>) -> Result<models::FooRefOrValue, Error<CreateFooError>> {
     // add a prefix to parameters to efficiently prevent name collisions
     let p_body_foo = foo;
@@ -67,6 +68,7 @@ pub fn create_foo(configuration: &configuration::Configuration, foo: Option<mode
     }
 }
 
+
 pub fn get_all_foos(configuration: &configuration::Configuration, ) -> Result<Vec<models::FooRefOrValue>, Error<GetAllFoosError>> {
 
     let uri_str = format!("{}/foo", configuration.base_path);

samples/client/petstore/rust/reqwest/name-mapping/src/apis/fake_api.rs

@@ -23,6 +23,7 @@ pub enum GetParameterNameMappingError {
 }
 
 
+
 pub fn get_parameter_name_mapping(configuration: &configuration::Configuration, underscore_type: i64, r#type: &str, type_with_underscore: &str, dash_type: &str, http_debug_option: &str) -> Result<(), Error<GetParameterNameMappingError>> {
     // add a prefix to parameters to efficiently prevent name collisions
     let p_header_underscore_type = underscore_type;