private static String arrayToString(boolean[] a) {
    StringBuilder b = new StringBuilder();
    b.append('[');
    for (int i = 0; i < a.length; ++i) {
      b.append(a[i] ? "1" : "0");
    }
    b.append(']');
    return b.toString();
  }
Estimate the RowGroup offset given the next RG offset and isLast.

@param isCompressed is the RowGroup compressed
@param isLast is this the last RowGroup
@param nextGroupOffset the offset of the next RowGroup
@param streamLength the length of the whole Stream
@param bufferSize the size of the buffer
@return
ql/src/java/org/apache/hadoop/hive/ql/io/orc/encoded/EncodedReaderImpl.java