code: private void addDescriptor(List<String> result, EntityDescriptor descriptor) throws MetadataProviderException {
  
          String entityID = descriptor.getEntityID();
          log.debug("Found metadata EntityDescriptor with ID", entityID);
          result.add(entityID);
  
      }
docs: Parses entityID from the descriptor and adds it to the result set.  Signatures on all found entities
  are verified using the given policy and trust engine.
  
  @param result     result set
  @param descriptor descriptor to parse
  @throws MetadataProviderException in case signature validation fails