SDP (Sockets Direct Protocol) has been obsolete for more than a decade[1], is no longer maintained on any major platform, and cannot be used on modern systems. This issue requests to the remove the SDP support[2] from JDK.

[1]: For instance, there was never a native Linux kernel version that officially supported `AF_INET_SDP` built-in. Support was provided via the out-of-tree `ib_sdp` module distributed with older OFED (Open Fabrics Enterprise Distribution) releases. That module was dropped around 2012–2013, and no mainstream kernel since ~3.x supports it.
[2]: https://docs.oracle.com/javase/tutorial/sdp/sockets/supported.html