net/src/main/java/com/stanfy/enroscar/rest/request/net/multipart/Part.java
public long length() throws IOException {
    if (DEBUG) { Log.v(TAG, "enter length()"); }
    if (lengthOfData() < 0) {
      return -1;
    }
    final ByteArrayOutputStream overhead = new ByteArrayOutputStream();
    sendStart(overhead);
    sendDispositionHeader(overhead);
    sendContentTypeHeader(overhead);
    sendTransferEncodingHeader(overhead);
    sendEndOfHeader(overhead);
    sendEnd(overhead);
    return overhead.size() + lengthOfData();
  }
public long length() throws IOException {
    if (DEBUG) { Log.v(TAG, "enter length()"); }
    if (lengthOfData() < 0) {
      return -1;
    }
    final ByteArrayOutputStream overhead = new ByteArrayOutputStream();
    sendStart(overhead);
    sendDispositionHeader(overhead);
    sendContentTypeHeader(overhead);
    sendTransferEncodingHeader(overhead);
    sendEndOfHeader(overhead);
    sendEnd(overhead);
    return overhead.size() + lengthOfData();
  }
Return the full length of all the data.
If you override this method make sure to override
#send(OutputStream) as well

@return long The length.
@throws IOException If an IO problem occurs