code: public static String[] getExtends(Configuration config, String module, String[] defaultExtensions) {
          String extension = getStringExtends(config, module);
  
          if (StringUtils.isBlank(extension)) {
              return defaultExtensions;
          } else {
              extension = extension.toLowerCase();
          }
          String[] extensions = extension.split(",");
          for (String ext : defaultExtensions) {
              if (!ArrayUtils.contains(extensions, ext.substring(1))
                      && !ArrayUtils.contains(extensions, ext)) {
                  extensions = ArrayUtils.add(extensions, ext);
              }
          }
          return extensions;
      }
docs: <p>getExtends.</p>
  
  @param config a {@link javax.ws.rs.core.Configuration} object.
  @param module a {@link java.lang.String} object.
  @param defaultExtensions an array of {@link java.lang.String} objects.
  @return an array of {@link java.lang.String} objects.