AVAssetResourceLoader's dataRequest requestedLength

We are trying to implement custom decryption of an AVPlayerItem. We use AVAssetResourceLoaderDelegate for manual request to the server which has byte range support. First request which we intercepts in the resource loader is contentInformationRequest, and second and the third one are dataRequests. First dataRequest contains requestedLength of 65536 B and if we manually forward it to the server we gets 65536 B as expected. We than return that data to the resourceLoader and finish loadingRequest. When next dataRequest comes to the resourceLoader delegate, it contains requestedLength for the entire remaining length of the resource. Why resourceLoader set requestedLength to the entire remaining length of the resource? (prior to second data request, requestsAllDataToEndOfResource becomes true)

First dataRequest
current offset: 0, requested length: 65536, requested offset 0

request: Optional(["Accept": "*/*", "Range": "bytes=0-65535"])
 { URL: http://cdn.blabla.com/HRA040827496/v01/HRA040827496.mp3 } { Status Code: 206, Headers {
    "Cache-Control" =     (
        "max-age=7776000"
    );
    Connection =     (
        "keep-alive"
    );
    "Content-Length" =     (
        65536
    );
    "Content-Range" =     (
        "bytes 0-65535/9828342"
    );
    "Content-Type" =     (
        "audio/mpeg"
    );
    Date =     (
        "Fri, 09 Nov 2018 12:04:17 GMT"
    );
    Etag =     (
        "\"5ae2f3b4-95f7f6\""
    );
    Expires =     (
        "Thu, 07 Feb 2019 12:04:17 GMT"
    );
    "Last-Modified" =     (
        "Fri, 27 Apr 2018 09:56:04 GMT"
    );
    Server =     (
        "nginx/1.10.2"
    );
} }

Second dataRequest
current offset: 65536, requested length: 9762806, requested offset 65536

request: Optional(["Accept": "*/*", "Range": "bytes=65536-9828341"])
 { URL: http://cdn.blabla.com/HRA040827496/v01/HRA040827496.mp3 } { Status Code: 206, Headers {
    "Cache-Control" =     (
        "max-age=7776000"
    );
    Connection =     (
        "keep-alive"
    );
    "Content-Length" =     (
        9762806
    );
    "Content-Range" =     (
        "bytes 65536-9828341/9828342"
    );
    "Content-Type" =     (
        "audio/mpeg"
    );
    Date =     (
        "Fri, 09 Nov 2018 12:04:18 GMT"
    );
    Etag =     (
        "\"5ae2f3b4-95f7f6\""
    );
    Expires =     (
        "Thu, 07 Feb 2019 12:04:18 GMT"
    );
    "Last-Modified" =     (
        "Fri, 27 Apr 2018 09:56:04 GMT"
    );
    Server =     (
        "nginx/1.10.2"
    );
} }