I am adding a message to a gmail folder using this (example) URL:

```
https://www.googleapis.com/gmail/v1/users/user@domain.com/messages/import?uploadType=multipart

```

The body of the request looks like this:

```
--test_abc123
Content-Type: application/json; charset=UTF-8

{
 "labelIds": [ "Label_525" ],
 "raw": "RnJvbTogIlNlY3RpZ28gQ2VydGlmaWNh..."
}

--test_abc123--

```

The raw data is a base64 encoded standard MIME message that looks normal to me. The result of this POST is http error 400 with the error response "Payload parts count different from expected 2. Request payload parts count: 1".

I can supply the original MIME text if that is helpful, but let me emphasize that I have been running this code for several years without problem. I've tried different messages to test this out, but it appears that Google has changed something to break my software. 

Is Google objecting to my raw data, or something about the MIME encoding? Any ideas what the problem could be?

---- Addendum ----
I have gotten a few messages to work, they seem to all have image or data attachments. However I really don't see any problem with the messages that are failing - I can import them into Office 365 or Thunderbird or anything else and they render just fine. As a test, I tried importing the message below, which was taken from the MIME RFC. It fails with the same error. I think that Google has changed something to make their MIME parser very fussy, but I don't see how I can fix my input data.

```
From: Nathaniel Borenstein <nsb@bellcore.com>
To:  Ned Freed <ned@innosoft.com>
Subject: Sample message
MIME-Version: 1.0
Content-type: multipart/mixed; boundary="simple boundary"

This is the preamble.  It is to be ignored, though it
is a handy place for mail composers to include an
explanatory note to non-MIME compliant readers.
--simple boundary

This is implicitly typed plain ASCII text.
It does NOT end with a linebreak.
--simple boundary
Content-type: text/plain; charset=us-ascii

This is explicitly typed plain ASCII text.
It DOES end with a linebreak.

--simple boundary--
This is the epilogue.  It is also to be ignored.

```

Addendum 2: I tried a simple upload (using content-type header message/rfc822) and it worked, except the message was unlabeled. How
would I specify what label I want applied to a message? I was originally trying to follow the documentation here
[link](https://developers.google.com/gmail/api/v1/reference/users/messages/insert)
which tells me to create the json body that I gave above. This allows me to specify the label. But I cannot seem to use
this body in a simple upload. The content type is either invalid, or what Gmail imports is just literally the json body,
it does not parse out the raw data. If you could point me to a specific example showing the URI, message body, http headers
(not java code) that would be very useful to me.