private static synchronized void populateToken2Type() {
    if(token2Type != null){
      return;
    }
    token2Type = new HashMap<Integer, PrivilegeType>();
    for(PrivilegeType privType : PrivilegeType.values()){
      token2Type.put(privType.getToken(), privType);
    }
  }
Do case lookup of PrivilegeType associated with this antlr token
@param token
@return corresponding PrivilegeType
ql/src/java/org/apache/hadoop/hive/ql/security/authorization/PrivilegeType.java