refactor(SolidifyRestClientService): reuse getResource implementation

solidify-controller/src/main/java/ch/unige/solidify/service/SolidifyRestClientService.java

@@ -161,12 +161,7 @@ public abstract class SolidifyRestClientService {
   // *******************
 
   public String getResource(String url) {
-    final RestTemplate restClt = this.getRestTemplate(HttpMethod.GET);
-    try {
-      return restClt.getForObject(url, String.class);
-    } catch (final HttpClientErrorException e) {
-      throw this.getSolidifyExceptionFromHttpClientErrorException(url, e);
-    }
+    return this.getResource(url, String.class);
   }
 
   public <T> List<T> getResourceList(String url, Class<T[]> clazz) {