code: public static String getAutoGenDDLFromJar(InMemoryJarfile jarfile)
              throws IOException
      {
          // Read the raw auto generated ddl bytes.
          byte[] ddlBytes = jarfile.get(VoltCompiler.AUTOGEN_DDL_FILE_NAME);
          if (ddlBytes == null) {
              throw new IOException("Auto generated schema DDL not found - please make sure the database is initialized with valid schema.");
          }
          String ddl = new String(ddlBytes, StandardCharsets.UTF_8);
          return ddl.trim();
      }
docs: Get the auto generated DDL from the catalog jar.
  
  @param jarfile in-memory catalog jar file
  @return Auto generated DDL stored in catalog.jar
  @throws IOException If the catalog or the auto generated ddl cannot be loaded.