code: private void readPropertiesFiles() {
  
          if (this.configurationFileWildcard.isEmpty() || this.configurationFileExtension.isEmpty()) {
              // Skip configuration loading
              LOGGER.log(SKIP_CONF_LOADING);
  
          } else {
              // Assemble the regex pattern
              final Pattern filePattern = Pattern.compile(this.configurationFileWildcard + "\\." + this.configurationFileExtension);
  
              // Retrieve all resources from default classpath
              final Collection<String> list = ClasspathUtility.getClasspathResources(filePattern);
  
              LOGGER.log(CONFIG_FOUND, list.size(), list.size() > 1 ? "s" : "");
  
              for (final String confFilename : list) {
                  readPropertiesFile(confFilename);
              }
          }
      }
docs: Read all configuration files available into the application classpath.