docs: protected String buildSparqlQueryToFindUser(final String userIdentifier, boolean findAllUsers)
      {
          if(!findAllUsers && userIdentifier == null)
          {
              throw new NullPointerException("User identifier was null");
          }
          
          final StringBuilder query = new StringBuilder();
          
          query.append(" SELECT ?userIdentifier ?userUri ?userSecret ?userFirstName ?userLastName ?userEmail ");
          query.append(" WHERE ");
          query.append(" { ");
          query.append("   ?userUri a ");
          query.append(RenderUtils.getSPARQLQueryString(SesameRealmConstants.OAS_USER));
          query.append(" . ");
          query.append("   ?userUri ");
          query.append(RenderUtils.getSPARQLQueryString(SesameRealmConstants.OAS_USERIDENTIFIER));
          query.append(" ?userIdentifier . ");
          query.append("   OPTIONAL{ ?userUri ");
          query.append(RenderUtils.getSPARQLQueryString(SesameRealmConstants.OAS_USERSECRET));
          query.append(" ?userSecret . } ");
          query.append("   OPTIONAL{ ?userUri ");
          query.append(RenderUtils.getSPARQLQueryString(SesameRealmConstants.OAS_USERFIRSTNAME));
          query.append(" ?userFirstName . } ");
          query.append("   OPTIONAL{ ?userUri ");
          query.append(RenderUtils.getSPARQLQueryString(SesameRealmConstants.OAS_USERLASTNAME));
          query.append(" ?userLastName . } ");
          query.append("   OPTIONAL{ ?userUri ");
          query.append(RenderUtils.getSPARQLQueryString(SesameRealmConstants.OAS_USEREMAIL));
          query.append(" ?userEmail . } ");
          if(!findAllUsers)
          {
              query.append("   FILTER(str(?userIdentifier) = \"" + RenderUtils.escape(userIdentifier) + "\") ");
          }
          query.append(" } ");
          return query.toString();
      }