Cookie handling does not conform to RFC 6265 when sending multiple cookies

[Sébastien Deleuze]

As discussed in spring-projects/spring-framework#26451, Reactor Netty creates multiple distinct header entries when creating multiple cookies which is not spec compliant. I have create a reproducer with Spring Boot 3.2.0 on https://github.com/sdeleuze/demo-webclient-cookies.

With ReactorClientHttpConnector I see:

+--------+-------------------------------------------------+----------------+
|00000000| 47 45 54 20 2f 20 48 54 54 50 2f 31 2e 31 0d 0a |GET / HTTP/1.1..|
|00000010| 61 63 63 65 70 74 2d 65 6e 63 6f 64 69 6e 67 3a |accept-encoding:|
|00000020| 20 67 7a 69 70 0d 0a 75 73 65 72 2d 61 67 65 6e | gzip..user-agen|
|00000030| 74 3a 20 52 65 61 63 74 6f 72 4e 65 74 74 79 2f |t: ReactorNetty/|
|00000040| 31 2e 31 2e 31 33 0d 0a 68 6f 73 74 3a 20 6c 6f |1.1.13..host: lo|
|00000050| 63 61 6c 68 6f 73 74 3a 38 30 38 30 0d 0a 61 63 |calhost:8080..ac|
|00000060| 63 65 70 74 3a 20 2a 2f 2a 0d 0a 63 6f 6f 6b 69 |cept: */*..cooki|
|00000070| 65 3a 20 63 6f 6f 6b 69 65 31 3d 66 6f 6f 0d 0a |e: cookie1=foo..|
|00000080| 63 6f 6f 6b 69 65 3a 20 63 6f 6f 6b 69 65 32 3d |cookie: cookie2=|
|00000090| 62 61 72 0d 0a 0d 0a                            |bar....         |
+--------+-------------------------------------------------+----------------+

With JdkClientHttpConnector I see:

+--------+-------------------------------------------------+----------------+
|00000000| 47 45 54 20 2f 20 48 54 54 50 2f 31 2e 31 0d 0a |GET / HTTP/1.1..|
|00000010| 43 6f 6e 6e 65 63 74 69 6f 6e 3a 20 55 70 67 72 |Connection: Upgr|
|00000020| 61 64 65 2c 20 48 54 54 50 32 2d 53 65 74 74 69 |ade, HTTP2-Setti|
|00000030| 6e 67 73 0d 0a 43 6f 6e 74 65 6e 74 2d 4c 65 6e |ngs..Content-Len|
|00000040| 67 74 68 3a 20 30 0d 0a 48 6f 73 74 3a 20 6c 6f |gth: 0..Host: lo|
|00000050| 63 61 6c 68 6f 73 74 3a 38 30 38 30 0d 0a 48 54 |calhost:8080..HT|
|00000060| 54 50 32 2d 53 65 74 74 69 6e 67 73 3a 20 41 41 |TP2-Settings: AA|
|00000070| 45 41 41 45 41 41 41 41 49 41 41 41 41 42 41 41 |EAAEAAAAIAAAABAA|
|00000080| 4d 41 41 41 42 6b 41 41 51 42 41 41 41 41 41 41 |MAAABkAAQBAAAAAA|
|00000090| 55 41 41 45 41 41 0d 0a 55 70 67 72 61 64 65 3a |UAAEAA..Upgrade:|
|000000a0| 20 68 32 63 0d 0a 55 73 65 72 2d 41 67 65 6e 74 | h2c..User-Agent|
|000000b0| 3a 20 4a 61 76 61 2d 68 74 74 70 2d 63 6c 69 65 |: Java-http-clie|
|000000c0| 6e 74 2f 31 37 2e 30 2e 37 0d 0a 41 63 63 65 70 |nt/17.0.7..Accep|
|000000d0| 74 3a 20 2a 2f 2a 0d 0a 43 6f 6f 6b 69 65 3a 20 |t: */*..Cookie: |
|000000e0| 63 6f 6f 6b 69 65 31 3d 66 6f 6f 3b 63 6f 6f 6b |cookie1=foo;cook|
|000000f0| 69 65 32 3d 62 61 72 0d 0a 0d 0a                |ie2=bar....     |
+--------+-------------------------------------------------+----------------+