sun/net/www/http/HttpClient/MultiThreadTest Failing after KeepAliveCache Backport

blocked threads with KeepAliveCache.get backport (https://bugs.openjdk.org/browse/JDK-8296117)
Is causing MultiThreadTest to fail with the following error:
https://mach5.us.oracle.com/mdash/builds/jdk-11.0.19+1-39/results?search=status%3Afailed%20AND%20-state%3Ainvalid
worker: 7: Shutdown
worker: 1: Shutdown
worker: 5: Shutdown
worker: 3: Shutdown
worker: 6: Shutdown
worker: 7 end - PT15.02540052S
worker: 5 end - PT15.02718247S
worker: 3 end - PT15.0562644S
worker: 6 end - PT15.02719008S
worker: 1 end - PT15.0570011S
----------System.err:(44/2698)----------
java.lang.RuntimeException: Expected 5 connections: used 8
at MultiThreadTest.main(MultiThreadTest.java:161)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at com.sun.javatest.regtest.agent.MainActionHelper$AgentVMRunnable.run(MainActionHelper.java:298)
at java.base/java.lang.Thread.run(Thread.java:834)
JavaTest Message: Test threw exception: java.lang.RuntimeException
JavaTest Message: shutting down test
JavaTest Message: Problem cleaning up the following threads:
Thread-19
  at java.base@11.0.19-ea/java.net.SocketInputStream.socketRead0(Native Method)
  at java.base@11.0.19-ea/java.net.SocketInputStream.socketRead(SocketInputStream.java:115)
  at java.base@11.0.19-ea/java.net.SocketInputStream.read(SocketInputStream.java:168)
  at java.base@11.0.19-ea/java.net.SocketInputStream.read(SocketInputStream.java:140)
  at java.base@11.0.19-ea/java.io.BufferedInputStream.fill(BufferedInputStream.java:252)
  at java.base@11.0.19-ea/java.io.BufferedInputStream.read(BufferedInputStream.java:271)
  at Worker.readUntil(MultiThreadTest.java:272)
  at Worker.run(MultiThreadTest.java:304)
Thread-21
  at java.base@11.0.19-ea/java.net.SocketInputStream.socketRead0(Native Method)
  at java.base@11.0.19-ea/java.net.SocketInputStream.socketRead(SocketInputStream.java:115)
  at java.base@11.0.19-ea/java.net.SocketInputStream.read(SocketInputStream.java:168)
  at java.base@11.0.19-ea/java.net.SocketInputStream.read(SocketInputStream.java:140)
  at java.base@11.0.19-ea/java.io.BufferedInputStream.fill(BufferedInputStream.java:252)
  at java.base@11.0.19-ea/java.io.BufferedInputStream.read(BufferedInputStream.java:271)
  at Worker.readUntil(MultiThreadTest.java:272)
  at Worker.run(MultiThreadTest.java:304)
Thread-23
  at java.base@11.0.19-ea/java.net.SocketInputStream.socketRead0(Native Method)
  at java.base@11.0.19-ea/java.net.SocketInputStream.socketRead(SocketInputStream.java:115)
  at java.base@11.0.19-ea/java.net.SocketInputStream.read(SocketInputStream.java:168)
  at java.base@11.0.19-ea/java.net.SocketInputStream.read(SocketInputStream.java:140)
  at java.base@11.0.19-ea/java.io.BufferedInputStream.fill(BufferedInputStream.java:252)
  at java.base@11.0.19-ea/java.io.BufferedInputStream.read(BufferedInputStream.java:271)
  at Worker.readUntil(MultiThreadTest.java:272)
  at Worker.run(MultiThreadTest.java:304)
result: Error. Error while cleaning up threads after test
test result: Error. Error while cleaning up threads after test