[python-nextgen] add support for StrictBytes (#15365)

* add strictbyte support in python-nextgen client

* update samples

* use union of strictbytes, strictstr for backward compatibility

samples/client/echo_api/java/feign-gson/src/main/java/org/openapitools/client/api/BodyApi.java

@@ -43,6 +43,35 @@ public interface BodyApi extends ApiClient.Api {
 
 
 
+  /**
+   * Test body parameter(s)
+   * Test body parameter(s)
+   * @param body  (optional)
+   * @return String
+   */
+  @RequestLine("POST /body/application/octetstream/binary")
+  @Headers({
+    "Content-Type: application/octet-stream",
+    "Accept: text/plain",
+  })
+  String testBodyApplicationOctetstreamBinary(File body);
+
+  /**
+   * Test body parameter(s)
+   * Similar to <code>testBodyApplicationOctetstreamBinary</code> but it also returns the http response headers .
+   * Test body parameter(s)
+   * @param body  (optional)
+   * @return A ApiResponse that wraps the response boyd and the http headers.
+   */
+  @RequestLine("POST /body/application/octetstream/binary")
+  @Headers({
+    "Content-Type: application/octet-stream",
+    "Accept: text/plain",
+  })
+  ApiResponse<String> testBodyApplicationOctetstreamBinaryWithHttpInfo(File body);
+
+
+
   /**
    * Test free form object
    * Test free form object