Program: 21131
Project: 21131
Buggy source:
/** 
 * <p> Calls   {@link OAuth2Credentials#refreshAccessToken()}. In case of an IOException, retry the call as per the   {@link Backoff} policy defined by {@link RetryOptions#createBackoff()}. </p> <p> This method retries until one of the following conditions occurs: <ol> <li>An OAuth request was completed. If the value is null, return an exception. <li>A non-IOException Exception is thrown - return an error status <li>All retries have been exhausted, i.e. when the Backoff.nextBackOffMillis() returns BackOff.STOP <li>An interrupt occurs. </ol>
 * @param backoff defines the current state of the retries. Initially, the value is null. In thecase of an  {@link IOException}, create a new   {@link BackOff}; see  {@link RetryOptions#createBackoff()} for more details on the initial construction. Ifa retry already occurred, the Backoff have the logic to get the next sleep period and retry exhaustion logic.
 * @return HeaderCacheElement containing either a valid {@link AccessToken} or an exception.
 */
protected HeaderCacheElement refreshCredentialsWithRetry(){
  BackOff backoff=null;
  while (true) {
    try {
      logger.info("String_Node_Str");
      AccessToken newToken=credentials.refreshAccessToken();
      if (newToken == null) {
        logger.info("String_Node_Str");
        return new HeaderCacheElement(new IOException("String_Node_Str" + credentials));
      }
 else {
        return new HeaderCacheElement(newToken);
      }
    }
 catch (    IOException exception) {
      logger.warn("String_Node_Str",exception);
      if (backoff == null) {
        backoff=retryOptions.createBackoff();
      }
      try {
        RetryState retryState=getRetryState(backoff);
        if (retryState != RetryState.PerformRetry) {
          return new HeaderCacheElement(exception);
        }
      }
 catch (      IOException e) {
        logger.warn("String_Node_Str",e);
        return new HeaderCacheElement(exception);
      }
    }
catch (    Exception e) {
      logger.warn("String_Node_Str",e);
      return new HeaderCacheElement(new IOException("String_Node_Str",e));
    }
  }
}

Fixed version (ground truth):
/** 
 * <p> Calls   {@link OAuth2Credentials#refreshAccessToken()}. In case of an IOException, retry the call as per the   {@link BackOff} policy defined by {@link RetryOptions#createBackoff()}. </p> <p> This method retries until one of the following conditions occurs: <ol> <li>An OAuth request was completed. If the value is null, return an exception. <li>A non-IOException Exception is thrown - return an error status <li>All retries have been exhausted, i.e. when the Backoff.nextBackOffMillis() returns BackOff.STOP <li>An interrupt occurs. </ol>
 * @return HeaderCacheElement containing either a valid {@link AccessToken} or an exception.
 */
protected HeaderCacheElement refreshCredentialsWithRetry(){
  BackOff backoff=null;
  while (true) {
    try {
      logger.info("String_Node_Str");
      AccessToken newToken=credentials.refreshAccessToken();
      if (newToken == null) {
        logger.info("String_Node_Str");
        return new HeaderCacheElement(new IOException("String_Node_Str" + credentials));
      }
 else {
        return new HeaderCacheElement(newToken);
      }
    }
 catch (    IOException exception) {
      logger.warn("String_Node_Str",exception);
      if (backoff == null) {
        backoff=retryOptions.createBackoff();
      }
      try {
        RetryState retryState=getRetryState(backoff);
        if (retryState != RetryState.PerformRetry) {
          return new HeaderCacheElement(exception);
        }
      }
 catch (      IOException e) {
        logger.warn("String_Node_Str",e);
        return new HeaderCacheElement(exception);
      }
    }
catch (    Exception e) {
      logger.warn("String_Node_Str",e);
      return new HeaderCacheElement(new IOException("String_Node_Str",e));
    }
  }
}