[python] Add tests and fix enum path parameters (#16769)

* test: Tests for enum params in path, query and header

* fix: Get enum ref values correctly in path parameters

Closes #16688

* fix java tests failure

---------

Co-authored-by: William Cheng <wing328hk@gmail.com>

samples/client/echo_api/java/native/api/openapi.yaml

@@ -11,10 +11,10 @@ info:
 servers:
 - url: http://localhost:3000/
 paths:
-  /path/string/{path_string}/integer/{path_integer}:
+  /path/string/{path_string}/integer/{path_integer}/{enum_nonref_string_path}/{enum_ref_string_path}:
     get:
       description: Test path parameter(s)
-      operationId: "tests/path/string/{path_string}/integer/{path_integer}"
+      operationId: "tests/path/string/{path_string}/integer/{path_integer}/{enum_nonref_string_path}/{enum_ref_string_path}"
       parameters:
       - explode: false
         in: path
@@ -30,6 +30,24 @@ paths:
         schema:
           type: integer
         style: simple
+      - explode: false
+        in: path
+        name: enum_nonref_string_path
+        required: true
+        schema:
+          enum:
+          - success
+          - failure
+          - unclassified
+          type: string
+        style: simple
+      - explode: false
+        in: path
+        name: enum_ref_string_path
+        required: true
+        schema:
+          $ref: '#/components/schemas/StringEnumRef'
+        style: simple
       responses:
         "200":
           content:
@@ -83,10 +101,10 @@ paths:
       - form
       x-content-type: application/x-www-form-urlencoded
       x-accepts: text/plain
-  /header/integer/boolean/string:
+  /header/integer/boolean/string/enums:
     get:
       description: Test header parameter(s)
-      operationId: test/header/integer/boolean/string
+      operationId: test/header/integer/boolean/string/enums
       parameters:
       - explode: true
         in: header
@@ -109,6 +127,24 @@ paths:
         schema:
           type: string
         style: form
+      - explode: true
+        in: header
+        name: enum_nonref_string_header
+        required: false
+        schema:
+          enum:
+          - success
+          - failure
+          - unclassified
+          type: string
+        style: form
+      - explode: true
+        in: header
+        name: enum_ref_string_header
+        required: false
+        schema:
+          $ref: '#/components/schemas/StringEnumRef'
+        style: form
       responses:
         "200":
           content:
@@ -125,6 +161,17 @@ paths:
       description: Test query parameter(s)
       operationId: test/enum_ref_string
       parameters:
+      - explode: true
+        in: query
+        name: enum_nonref_string_query
+        required: false
+        schema:
+          enum:
+          - success
+          - failure
+          - unclassified
+          type: string
+        style: form
       - explode: true
         in: query
         name: enum_ref_string_query