private ByteBuffer serializeCredentials(Credentials credentials) throws IOException {
    Credentials containerCredentials = new Credentials();
    containerCredentials.addAll(credentials);
    DataOutputBuffer containerTokens_dob = new DataOutputBuffer();
    containerCredentials.writeTokenStorageToStream(containerTokens_dob);
    return ByteBuffer.wrap(containerTokens_dob.getData(), 0, containerTokens_dob.getLength());
  }
Close all outstanding connections created by getSplits() calls
llap-ext-client/src/java/org/apache/hadoop/hive/llap/LlapBaseInputFormat.java