protected Set<LdapUserDto> getExternalLdapUserInfo() {
    LdapServerProperties ldapServerProperties = getLdapProperties();
    EqualsFilter userObjectFilter = new EqualsFilter(OBJECT_CLASS_ATTRIBUTE,
        ldapServerProperties.getUserObjectClass());
    return getFilteredLdapUsers(ldapServerProperties.getBaseDN(), userObjectFilter);
  }
Retrieves users from external LDAP server.

@return set of info about LDAP users
ambari-server/src/main/java/org/apache/ambari/server/security/ldap/AmbariLdapDataPopulator.java