FlateDecode.Encode writes zlib streams without the Adler-32 trailer (RFC 1950) #397

var data = Encoding.ASCII.GetBytes("Wikipedia");
var encoded = new FlateDecode().Encode(data);
// Expected: encoded ends with 11 E6 03 98 (Adler-32 of "Wikipedia")
// Actual:   encoded ends with the last byte of the deflate data

import zlib
d = zlib.decompressobj()
d.decompress(encoded)
print(d.eof)   # False - stream incomplete; zlib.decompress(encoded) raises an error

            zip.Close();

            // RFC 1950 requires the Adler-32 checksum of the uncompressed data after the deflate data
            // (big-endian). DeflateStream writes raw deflate only, so it must be appended here.
            var adler = ComputeAdler32(data);
            ms.WriteByte((byte)(adler >> 24));
            ms.WriteByte((byte)(adler >> 16));
            ms.WriteByte((byte)(adler >> 8));
            ms.WriteByte((byte)adler);

            ms.Capacity = (int)ms.Length;
            return ms.GetBuffer();
        }

        internal static uint ComputeAdler32(byte[] data)
        {
            const uint modAdler = 65521;
            // Largest n for which the sums cannot overflow before the modulo is applied.
            const int maxBlock = 5552;

            uint a = 1, b = 0;
            var offset = 0;
            var remaining = data.Length;
            while (remaining > 0)
            {
                var count = Math.Min(remaining, maxBlock);
                remaining -= count;
                while (count-- > 0)
                {
                    a += data[offset++];
                    b += a;
                }
                a %= modAdler;
                b %= modAdler;
            }
            return (b << 16) | a;
        }