code: public List<ResourceResolver> buildResolvers() {
  		List<ResourceResolver> resolvers = new ArrayList<>();
  		resolvers.addAll(customResolvers);
  		// ensure that default lookup is always the last registered
  		List<ResolverHelper> helpers = new ArrayList<>();
  		if (classPath != null) {
  			helpers.add(new ResolverHelper(classPath.getLookups(), classPath));
  		}
  		if (file != null) {
  			helpers.add(new ResolverHelper(file.getLookups(), file));
  		}
  		if (string != null) {
  			helpers.add(new ResolverHelper(string.getLookups(), string));
  		}
  		Collections.sort(helpers, new PrefixComparator());
  		for (ResolverHelper helper : helpers) {
  			helper.register(resolvers);
  		}
  		return resolvers;
  	}
docs: Build the list of resource resolvers.
  
  <p>
  The list is ordered to ensure that empty string lookup is always the last
  registered.
  </p>
  
  <p>
  If some custom resolvers are registered, they are used before default
  ones in the order they were registered.
  </p>
  
  @return the list of resource resolvers