code: private static String[] getAllowedMethods(String[] existingMethods) {
          int listCapacity = existingMethods.length + 1;
  
          List<String> allowedMethods = new ArrayList<>(listCapacity);
  
          allowedMethods.addAll(Arrays.asList(existingMethods));
          allowedMethods.add(METHOD_PATCH);
  
          return allowedMethods.toArray(new String[0]);
      }
docs: Appends PATCH to the provided array.
  
  @param existingMethods Methods that are, and must be, allowed.
  @return New array also containing PATCH.