A DESCRIPTION OF THE PROBLEM :
This enhancement request is for HttpClient to honor the namedGroups set on the configured SSLParameters.

Today you can set the namedGroups on the SSLParameters like so:

final SSLParameters sslParameters = new SSLParameters();
sslParameters.setNamedGroups(new String[]{namedGroup});
return HttpClient.newBuilder()
.sslContext(sslBundle.createSslContext())
.sslParameters(sslParameters)
.build();

When doing this today the namedGroups are dropped from the SSLParamters that are set on the HttpClient.

See Utils.java: https://github.com/openjdk/jdk/blob/master/src/java.net.http/share/classes/jdk/internal/net/http/common/Utils.java#L591