fix: handle void safety for Apache HttpClient

liferay-plugins-sdk-6.2/portlets/portos-firma-portlet/docroot/WEB-INF/src/it/tref/liferay/portos/firma/util/FirmaUtil.java

@@ -66,7 +66,9 @@ public class FirmaUtil {
 		} catch (IOException e) {
 			_log.error(e.getMessage());
 		} finally {
-			client.getConnectionManager().shutdown();
+			if(client != null){
+				client.getConnectionManager().shutdown();
+			}
 		}
 		return listaCodiciFiscali;
 	}