[11u] RFR: 216974: HttpConnection not returned to the pool after 204 response

[Lindenmaier, Goetz]

Hi,

I would like to downport this for parity with 11.0.9-oracle.

I had to do some simple resolved for this change:
http://cr.openjdk.java.net/~goetz/wr20/8216974-HttpConnection_1-jdk11/01/

ExchangeImpl.java: Copyright

Http1Exchange.java: 
One import did not apply because of different context.

Response204.java:
Adding the bug id in the test description failed because there
is already another one.
The new check for error could not be applied because there 
is an additional test call in the context (Test 3). I resolved
it similar as in jdk/jdk.

The VM compiles and the test is passing. 
Please review.

https://bugs.openjdk.java.net/browse/JDK-8216974
http://hg.openjdk.java.net/jdk/jdk/rev/54aa3ea04fe8

Best regards,
  Goetz.