Fix #25863: Use http_proxy system-properties in HttpClient of SAML

Co-authored-by: bleboeuf <bart.leboeuf@teamwork.net>

commit 558ccbea03ade2a5574e968eb76de1a3fbedd865
Author: bleboeuf <bart.leboeuf@teamwork.net>
Date:   Mon Mar 8 13:42:17 2021 +0100

    Fix: use java proxy variables

commit 60c9fc3d2f093a0e7fb9112fbbd3dc90f032719c
Author: bleboeuf <bart.leboeuf@teamwork.net>
Date:   Sat Mar 6 15:26:13 2021 +0100

    Feat: add corporate proxy support on httpClient used by saml configuration.

Author: LEDfan

src/main/java/eu/openanalytics/containerproxy/auth/impl/saml/SAMLConfiguration.java

@@ -22,6 +22,7 @@
 
 import eu.openanalytics.containerproxy.auth.UserLogoutHandler;
 import eu.openanalytics.containerproxy.auth.impl.SAMLAuthenticationBackend;
+import org.apache.commons.httpclient.HostConfiguration;
 import org.apache.commons.httpclient.HttpClient;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -261,17 +262,29 @@ public ExtendedMetadata extendedMetadata() {
 	}
 
 	@Bean
-	public ExtendedMetadataDelegate idpMetadata() throws MetadataProviderException, ResourceException {
+	public ExtendedMetadataDelegate idpMetadata() throws MetadataProviderException {
 		String metadataURL = environment.getProperty(PROP_METADATA_URL);
 
 		Timer backgroundTaskTimer = new Timer(true);
-		HTTPMetadataProvider httpMetadataProvider = new HTTPMetadataProvider(backgroundTaskTimer, new HttpClient(), metadataURL);   httpMetadataProvider.setParserPool(parserPool());
+		HTTPMetadataProvider httpMetadataProvider = new HTTPMetadataProvider(backgroundTaskTimer, getHttpClient(), metadataURL);
+		httpMetadataProvider.setParserPool(parserPool());
 		ExtendedMetadataDelegate extendedMetadataDelegate = new ExtendedMetadataDelegate(httpMetadataProvider , extendedMetadata());
 		extendedMetadataDelegate.setMetadataTrustCheck(false);
 		extendedMetadataDelegate.setMetadataRequireSignature(false);
 		return extendedMetadataDelegate;
 	}
 
+	private HttpClient getHttpClient() {
+		HttpClient httpClient = new HttpClient();
+		String proxyHost = System.getProperty("http.proxyHost");
+		if (proxyHost != null) {
+			HostConfiguration hostConfiguration = new HostConfiguration();
+			hostConfiguration.setProxy(proxyHost, Integer.parseInt(System.getProperty("http.proxyPort","80")));
+			httpClient.setHostConfiguration(hostConfiguration);
+		}
+		return httpClient;
+	}
+
 	@Bean
 	@Qualifier("metadata")
 	public CachingMetadataManager metadata() throws MetadataProviderException, ResourceException {