docs: static CompletableFuture<ClientResponse> processExplainDefaultProc(AdHocPlannedStmtBatch planBatch) {
          Database db = VoltDB.instance().getCatalogContext().database;
  
          // there better be one statement if this is really SQL
          // from a default procedure
          assert(planBatch.getPlannedStatementCount() == 1);
          AdHocPlannedStatement ahps = planBatch.getPlannedStatement(0);
          String sql = new String(ahps.sql, StandardCharsets.UTF_8);
          String explain = planBatch.explainStatement(0, db, false);
  
          VoltTable vt = new VoltTable(new VoltTable.ColumnInfo("STATEMENT_NAME", VoltType.STRING),
                  new VoltTable.ColumnInfo( "SQL_STATEMENT", VoltType.STRING),
                  new VoltTable.ColumnInfo( "EXECUTION_PLAN", VoltType.STRING));
          vt.addRow("sql0", sql, explain);
  
          ClientResponseImpl response =
                  new ClientResponseImpl(
                          ClientResponseImpl.SUCCESS,
                          ClientResponse.UNINITIALIZED_APP_STATUS_CODE,
                          null,
                          new VoltTable[] { vt },
                          null);
  
          CompletableFuture<ClientResponse> fut = new CompletableFuture<>();
          fut.complete(response);
          return fut;
      }