code: public ClassFilter decorateWithPackageNameFilters(ClassFilter filterToDecorate, List<String> userSpecifiedPrefixes) {
          DenyAllPackageNames denyAllPackageNames = new DenyAllPackageNames(filterToDecorate);
  
          //if user has specified package prefixes, restrict to those
          ClassFilter packagePrefixFilter = new AcceptNamedPackagePrefixes(denyAllPackageNames, userSpecifiedPrefixes);
  
           //always permit built in handlers, deny other chorus packages
          return new AlwaysAllowBuiltInPackageRule(packagePrefixFilter);
      }
docs: @return a ClassFilter chain to use when discovering Handler classes in the classpath
  
  @param filterToDecorate this filter will be decorated with extra rules to check package names
  @param userSpecifiedPrefixes any handler package prefixes specified by user