How to use

intersection

method

in

org.apache.drill.shaded.guava.com.google.common.collect.Sets

@Override
Set<E> createElementSet() {
 return Sets.intersection(multiset1.elementSet(), multiset2.elementSet());
}

/**
 * Checks if the proxy user is authorized to impersonate the target user based on the policies.
 *
 * @param proxyName  proxy user name
 * @param targetName target user name
 * @param policies   impersonation policies
 * @return true iff proxy user is authorized to impersonate the target user
 */
private static boolean hasImpersonationPrivileges(final String proxyName, final String targetName,
                         final List<ImpersonationPolicy> policies) {
 final UserGroupInformation proxyUgi = ImpersonationUtil.createProxyUgi(proxyName);
 final Set<String> proxyGroups = Sets.newHashSet(proxyUgi.getGroupNames());
 final UserGroupInformation targetUgi = ImpersonationUtil.createProxyUgi(targetName);
 final Set<String> targetGroups = Sets.newHashSet(targetUgi.getGroupNames());
 for (final ImpersonationPolicy definition : policies) {
  // check if proxy user qualifies within this policy
  if (definition.proxy_principals.users.contains(proxyName) ||
    !Sets.intersection(definition.proxy_principals.groups, proxyGroups).isEmpty()) {
   // check if target qualifies within this policy
   if (definition.target_principals.users.contains(targetName) ||
     definition.target_principals.users.contains(STAR) ||
     !Sets.intersection(definition.target_principals.groups, targetGroups).isEmpty() ||
     definition.target_principals.groups.contains(STAR)) {
    return true;
   }
  }
 }
 return false;
}