RFR: 8288717: Add a means to close idle connections in HTTP/2 connection pool [v3]

[Conor Cleary]

On Wed, 19 Oct 2022 09:13:10 GMT, Conor Cleary <ccleary at openjdk.org> wrote:

>> **Issue**
>> When using HTTP/2 with the HttpClient, it can often be necessary to close an idle Http2 Connection before a server sends a GOAWAY frame. For example, a server or cloud based tool could close a TCP connection silently when it is idle for too long resulting in ConnectionResetException being thrown by the HttpClient.
>> 
>> **Proposed Solution**
>> A new system property, `jdk.httpclient.idleConnectionTimeout`, was added and is used to specify in Milliseconds how long an idle connection (idle connections are those which have no currently active streams) for the HttpClient before the connection is closed.
>
> Conor Cleary has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - 8288717: Additional check for timeout firing
>  - 8288717: Shortened default keepalive time

src/java.net.http/share/classes/jdk/internal/net/http/HttpClientImpl.java line 1694:

> 1692: 
> 1693:     private Duration getIdleConnectionTimeoutProp() {
> 1694:         // Http 2 in prop name somewhere

Need to remove misc comment here

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PR: https://git.openjdk.org/jdk/pull/10183