code: protected String getSql(int version){
          Dialect dialect = ((SqlManagerImpl) sqlManager).getDialect();
          ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
          InputStream in = classLoader.getResourceAsStream(
                  String.format("%s/%s_%d.sql", packageName, dialect.getName().toLowerCase(), version));
  
          if(in == null){
              in = classLoader.getResourceAsStream(
                      String.format("%s/%d.sql", packageName, version));
  
              if(in == null){
                  return null;
              }
          }
  
          byte[] buf = IOUtil.readStream(in);
  	
  		return new String(buf, StandardCharsets.UTF_8);
  	
  	}
docs: Returns the SQL which located within a package specified by the packageName as
  "dialectname_version.sql" or "version.sql".
  
  @param version the version number
  @return SQL or null if the SQL file does not exist