[BUG] Broken Key Vault JCA test (HttpUtilTest)

[vcolin7]

Describe the bug
Recently the Key Vault pipelines have started failing with this error. I'm not sure if this is a recent change, but it's impeding our ability to merge requests and release new Key Vault library versions.

Exception or Stack Trace
Taken from here (Microsoft internal).

To Reproduce
Run a Key Vault pipeline or simply mvn clean install for the Key Vault JCA package.

Code Snippet
This test case in HttpUtilTest:

@Test
public void testCustomizedHttpsClient() {
    String url = "https://mvnrepository.com/";
    String result = HttpUtil.get(url, null);
    assertNotNull(result);
    assertFalse(result.isEmpty());
}

That calls this method on HttpUtil:

public static String get(String url, Map<String, String> headers) {
    String result = null;
    try (CloseableHttpClient client = buildClient()) {
        HttpGet httpGet = new HttpGet(url);
        if (headers != null) {
            headers.forEach(httpGet::addHeader);
        }
        httpGet.addHeader(USER_AGENT_KEY, USER_AGENT_VALUE);
        result = client.execute(httpGet, createResponseHandler());
    } catch (IOException ioe) {
        LOGGER.log(WARNING, "Unable to finish the http get request.", ioe);
    }
    return result;
}

Expected behavior
No tests should fail.

Setup (please complete the following information):

• OS: Windows 8
• IDE: N/A
• Library/Libraries: com.azure:azure-security-keyvault-jca:2.3.0-beta.1
• Java version: 8
• App Server/Environment: You can find the details here.

Information Checklist
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