$ find open/src -name HttpExchange.java | xargs grep --line-number "is close\." /dev/null
open/src/jdk.httpserver/share/classes/com/sun/net/httpserver/HttpExchange.java:46: * After reading the request body, the stream is close.

It's comforting to know the stream may be close, but it would be more reassuring to know it has been closed.