Stage 5 - full integration

design/authenticators/authn_jwt/authn-jwt-fetch-more-keys.md

@@ -449,6 +449,32 @@ non-functional - decoupling variables from main BL requirements.
    ![image](fetch-more-keys-stage-4.png)
    </div></details>
 
+5. Create new `FetchStaticSigningKey` class parses the `public-keys` variable value and returns a valid JWKS structure
+   <details><div>
+
+   FetchStaticSigningKey` class:
+   - partially implements ephemeral `FetchSigningKey` interface:
+   - `call` method receives `force_read` parameter, but ignores it
+   - `fetch_signing_key` method does not require implementation
+   - receives `signing_key` value in ctor
+   - parses and validates `signing_key` value in `call`
+     For reference see expected validation errors below and `CreateJwksFromHttpResponse.parse_jwks_response` 
+
+   `CreateSigningKeyProvider` class:
+   - creates and returns `FetchStaticSigningKey` class when `signing_key_type` is `STATIC`
+   - passes `signing_key` from `SigningKeySettings`
+
+   ![image](fetch-more-keys-stage-5.png)   
+
+   ### Expected validation errors
+   | **Error message** | **Description** |
+   |-------------------|-----------------|
+   | Signing key configuration is invalid: JSON parsing error from JSON gem                     | When the variable value is not a valid JSON |                                    
+   | Signing key configuration is invalid: `public-keys` `type` field value is missing or empty | When type field absent or has empty value   | 
+   | Signing key configuration is invalid: `public-keys` `type` field value {} is wrong         | When type field value is no `jwks`          |
+   | Signing key configuration is invalid: `public-keys` `value` field is missing or empty      | When value field absent or has empty value  |
+   </div></details>
+
 ### Flow Diagrams
 [//]: # "Describe flow of main scenarios in the system. The description should include if / else decisions and loops"