code: public static String getConfigurationDirectoryFromEnv() {
  		String location = System.getenv(ConfigConstants.ENV_FLINK_CONF_DIR);
  
  		if (location != null) {
  			if (new File(location).exists()) {
  				return location;
  			}
  			else {
  				throw new RuntimeException("The configuration directory '" + location + "', specified in the '" +
  					ConfigConstants.ENV_FLINK_CONF_DIR + "' environment variable, does not exist.");
  			}
  		}
  		else if (new File(CONFIG_DIRECTORY_FALLBACK_1).exists()) {
  			location = CONFIG_DIRECTORY_FALLBACK_1;
  		}
  		else if (new File(CONFIG_DIRECTORY_FALLBACK_2).exists()) {
  			location = CONFIG_DIRECTORY_FALLBACK_2;
  		}
  		else {
  			throw new RuntimeException("The configuration directory was not specified. " +
  					"Please specify the directory containing the configuration file through the '" +
  				ConfigConstants.ENV_FLINK_CONF_DIR + "' environment variable.");
  		}
  		return location;
  	}
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