docs: private void readPropertySourceFromLoader(String fileName, String filePath, PropertySourceLoader propertySourceLoader, List<PropertySource> propertySources) throws ConfigurationException {
          ResourceResolver resourceResolver = new ResourceResolver();
          Optional<ResourceLoader> resourceLoader = resourceResolver.getSupportingLoader(filePath);
          ResourceLoader loader = resourceLoader.orElse(FileSystemResourceLoader.defaultLoader());
          try {
              Optional<InputStream> inputStream = loader.getResourceAsStream(filePath);
              if (inputStream.isPresent()) {
                  Map<String, Object> properties = propertySourceLoader.read(fileName, inputStream.get());
                  propertySources.add(PropertySource.of(properties));
              }
          } catch (IOException e) {
              throw new ConfigurationException("Unsupported properties file: " + fileName);
          }
      }