java/net/httpclient/FlowAdapterPublisherTest.java intermittently failing with TestServer: start exception: java.io.IOException: Invalid preface

----------System.out:(46/3793)----------
[TestNG] Running:
  java/net/httpclient/FlowAdapterPublisherTest.java

config FlowAdapterPublisherTest.setup(): success
test FlowAdapterPublisherTest.testAPIExceptions(): success
You know it's summer in Ireland when the rain gets warmer.
test FlowAdapterPublisherTest.testByteBufferPublisherFixedLength("http://localhost:55461/http1/echo"): success
You know it's summer in Ireland when the rain gets warmer.
test FlowAdapterPublisherTest.testByteBufferPublisherFixedLength("https://localhost:55462/https1/echo"): success
You know it's summer in Ireland when the rain gets warmer.
test FlowAdapterPublisherTest.testByteBufferPublisherFixedLength("http://localhost:55463/http2/echo"): success
You know it's summer in Ireland when the rain gets warmer.
test FlowAdapterPublisherTest.testByteBufferPublisherFixedLength("https://localhost:55465/https2/echo"): success
You know it's summer in Ireland when the rain gets warmer.
test FlowAdapterPublisherTest.testByteBufferPublisherUnknownLength("http://localhost:55461/http1/echo"): success
You know it's summer in Ireland when the rain gets warmer.
test FlowAdapterPublisherTest.testByteBufferPublisherUnknownLength("https://localhost:55462/https1/echo"): success
You know it's summer in Ireland when the rain gets warmer.
test FlowAdapterPublisherTest.testByteBufferPublisherUnknownLength("http://localhost:55463/http2/echo"): success
You know it's summer in Ireland when the rain gets warmer.
test FlowAdapterPublisherTest.testByteBufferPublisherUnknownLength("https://localhost:55465/https2/echo"): success
God invented whiskey to keep the Irish from ruling the world.
test FlowAdapterPublisherTest.testMappedByteBufferPublisherFixedLength("http://localhost:55461/http1/echo"): success
God invented whiskey to keep the Irish from ruling the world.
test FlowAdapterPublisherTest.testMappedByteBufferPublisherFixedLength("https://localhost:55462/https1/echo"): success
God invented whiskey to keep the Irish from ruling the world.
test FlowAdapterPublisherTest.testMappedByteBufferPublisherFixedLength("http://localhost:55463/http2/echo"): success
God invented whiskey to keep the Irish from ruling the world.
test FlowAdapterPublisherTest.testMappedByteBufferPublisherFixedLength("https://localhost:55465/https2/echo"): success
God invented whiskey to keep the Irish from ruling the world.
test FlowAdapterPublisherTest.testMappedByteBufferPublisherUnknownLength("http://localhost:55461/http1/echo"): success
God invented whiskey to keep the Irish from ruling the world.
test FlowAdapterPublisherTest.testMappedByteBufferPublisherUnknownLength("https://localhost:55462/https1/echo"): success
God invented whiskey to keep the Irish from ruling the world.
test FlowAdapterPublisherTest.testMappedByteBufferPublisherUnknownLength("http://localhost:55463/http2/echo"): success
God invented whiskey to keep the Irish from ruling the world.
test FlowAdapterPublisherTest.testMappedByteBufferPublisherUnknownLength("https://localhost:55465/https2/echo"): success
test FlowAdapterPublisherTest.testPublishTooFew("http://localhost:55461/http1/echo"): success
test FlowAdapterPublisherTest.testPublishTooFew("https://localhost:55462/https1/echo"): success
test FlowAdapterPublisherTest.testPublishTooFew("http://localhost:55463/http2/echo"): success
test FlowAdapterPublisherTest.testPublishTooFew("https://localhost:55465/https2/echo"): success
test FlowAdapterPublisherTest.testPublishTooMany("http://localhost:55461/http1/echo"): success
test FlowAdapterPublisherTest.testPublishTooMany("https://localhost:55462/https1/echo"): success
test FlowAdapterPublisherTest.testPublishTooMany("http://localhost:55463/http2/echo"): success
test FlowAdapterPublisherTest.testPublishTooMany("https://localhost:55465/https2/echo"): success
Timeout refired 480 times
----------System.err:(88/4902)*----------
TestServer: New connection from Socket[addr=/127.0.0.1,port=55489,localport=55463]
TestServer: POST /http2/echo
Server: creating input stream for stream 1
Using handler for: /http2/echo
Sent response headers 200
TestServer: New connection from Socket[addr=/127.0.0.1,port=55490,localport=55465]
TestServer: POST /https2/echo
Server: creating input stream for stream 1
Using handler for: /https2/echo
Sent response headers 200
TestServer: New connection from Socket[addr=/127.0.0.1,port=55496,localport=55463]
TestServer: POST /http2/echo
Server: creating input stream for stream 1
Using handler for: /http2/echo
Sent response headers 200
TestServer: New connection from Socket[addr=/127.0.0.1,port=55497,localport=55465]
TestServer: POST /https2/echo
Server: creating input stream for stream 1
Using handler for: /https2/echo
Sent response headers 200
TestServer: New connection from Socket[addr=/127.0.0.1,port=55500,localport=55463]
TestServer: POST /http2/echo
Server: creating input stream for stream 1
Using handler for: /http2/echo
Sent response headers 200
TestServer: New connection from Socket[addr=/127.0.0.1,port=55501,localport=55465]
TestServer: POST /https2/echo
Server: creating input stream for stream 1
Using handler for: /https2/echo
Sent response headers 200
TestServer: New connection from Socket[addr=/127.0.0.1,port=55507,localport=55463]
TestServer: POST /http2/echo
Server: creating input stream for stream 1
Using handler for: /http2/echo
Sent response headers 200
TestServer: New connection from Socket[addr=/127.0.0.1,port=55508,localport=55465]
TestServer: POST /https2/echo
Server: creating input stream for stream 1
Using handler for: /https2/echo
Sent response headers 200
TestServer: New connection from Socket[addr=/127.0.0.1,port=55513,localport=55463]
Server connection to /127.0.0.1:55513 stopping. 0 streams
TestServer: start exception: java.io.IOException: Invalid preface: \u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000
TestServer: New connection from Socket[addr=/127.0.0.1,port=55514,localport=55465]
TestServer: POST /https2/echo
Server: creating input stream for stream 1
Using handler for: /https2/echo
Sent response headers 200
TestServer: Stream 1 closed: java.io.IOException: closed
TestServer: New connection from Socket[addr=/127.0.0.1,port=55524,localport=55463]
Server connection to /127.0.0.1:55524 stopping. 0 streams
TestServer: start exception: java.io.IOException: Invalid preface: \u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000
TestServer: New connection from Socket[addr=/127.0.0.1,port=55525,localport=55465]
TestServer: POST /https2/echo
Server: creating input stream for stream 1
Using handler for: /https2/echo
Sent response headers 200
TestServer: Stream 1 closed: java.io.IOException: closed
Closing: GOAWAY: length=25, streamid=0, flags=0 Error: Not an error Debugdata: Requested by user
Server connection to /127.0.0.1:55489 stopping. 1 streams
TestServer: Connection writer stopping
Closing: GOAWAY: length=25, streamid=0, flags=0 Error: Not an error Debugdata: Requested by user
Server connection to /127.0.0.1:55490 stopping. 1 streams
TestServer: Connection writer stopping
Closing: GOAWAY: length=25, streamid=0, flags=0 Error: Not an error Debugdata: Requested by user
Server connection to /127.0.0.1:55496 stopping. 1 streams
Closing: GOAWAY: length=25, streamid=0, flags=0 Error: Not an error Debugdata: Requested by user
Server connection to /127.0.0.1:55497 stopping. 1 streams
TestServer: Connection writer stopping
TestServer: Connection writer stopping
Closing: GOAWAY: length=25, streamid=0, flags=0 Error: Not an error Debugdata: Requested by user
Server connection to /127.0.0.1:55500 stopping. 1 streams
Closing: GOAWAY: length=25, streamid=0, flags=0 Error: Not an error Debugdata: Requested by user
Server connection to /127.0.0.1:55507 stopping. 1 streams
Closing: GOAWAY: length=25, streamid=0, flags=0 Error: Not an error Debugdata: Requested by user
Server connection to /127.0.0.1:55501 stopping. 1 streams
TestServer: Connection writer stopping
TestServer: Connection writer stopping
TestServer: Connection writer stopping
Closing: GOAWAY: length=25, streamid=0, flags=0 Error: Not an error Debugdata: Requested by user
Server connection to /127.0.0.1:55508 stopping. 1 streams
Closing: GOAWAY: length=25, streamid=0, flags=0 Error: Not an error Debugdata: Requested by user
TestServer: Connection writer stopping
Server connection to /127.0.0.1:55514 stopping. 1 streams
TestServer: Connection writer stopping
Closing: GOAWAY: length=25, streamid=0, flags=0 Error: Not an error Debugdata: Requested by user
Server connection to /127.0.0.1:55525 stopping. 1 streams
TestServer: Connection writer stopping