Problem Description
### Oracle Vector Search Verification Report: Malfunction of DBMS_VECTOR_CHAIN
#### 1. Overview
Vector generation using `DBMS_VECTOR_CHAIN.UTL_TO_EMBEDDINGS` fails to function, generating errors despite a valid API key and network connectivity being present.
Verification conducted on both standard OpenAI and Azure OpenAI resulted in distinct errors, but both suggest **"as the environment succeeds with external `curl` etc., this points to a bug within the Oracle package or a specification constraint"**.
This issue occurs only on multiple Always Free instances and has not been observed on paid instances.
#### 2. Verification Environment
* **Executing User:** `SHINKI_DEMO`
* **DB Version:** Oracle Database 23ai (detailed version)
* **Network:** ACLs (`connect`, `resolve`, `http`) granted for `api.openai.com` and Azure endpoints. Proxy configured.
#### 3. Occurring Phenomenon and Error
**Case A: Standard OpenAI (Provider: openai)**
* **Behaviour:** Appears to fail internally when attempting to retrieve credentials.
* **Error:** `ORA-20003: error retrieving credential`
* **Additional Notes:** Manual implementation using `UTL_HTTP` succeeds (Status 200) with the same key.
**Case B: Azure OpenAI**
* **Behaviour:** The request is being sent, but Azure is rejecting it as "invalid authentication".
* **Error:**
```text
ORA-20002: The provider returned an error - Access denied due to invalid subscription key or wrong API endpoint.
Make sure to provide