The assertion that fires is at DependentPromiseActionsTest.java:366:
   
         assert subscriberType == SubscriberType.LAZZY || !responseCF.isDone();

[2 s, 962 ms, 175524 ns] testAsStringAsync(https://localhost:62490/https2/fixed/y, true, SemaphoreStaller)
try stalling in BODY_HANDLER
Http2TestContext::handle Http2TestExchangeImpl: Http2TestExchangeImpl@7adafea8
HTTP_FixedLengthHandler received request to https://localhost:62490/https2/fixed/y
TestServer: [2 s, 966 ms, 259293 ns] Pushing promise: https://localhost:62490/https2/fixed/y/before/promise-1
TestServer: [2 s, 966 ms, 894323 ns] Pushing promise: https://localhost:62490/https2/fixed/y/after/promise-2
TestServer: [2 s, 967 ms, 343972 ns] Pushing promise: https://localhost:62490/https2/fixed/y/after/promise-3
Found expected frame: java.net.http/jdk.internal.net.http.PrivilegedExecutor$PrivilegedRunnable.lambda$run$0(PrivilegedExecutor.java:60)
Found expected frame: java.net.http/jdk.internal.net.http.PrivilegedExecutor$PrivilegedRunnable.lambda$run$0(PrivilegedExecutor.java:60)
test DependentPromiseActionsTest.testAsStringAsync("https://localhost:62490/https2/fixed/y", true, SemaphoreStaller): failure
java.lang.AssertionError
at DependentPromiseActionsTest.testDependent(DependentPromiseActionsTest.java:366)
at DependentPromiseActionsTest.testDependent(DependentPromiseActionsTest.java:336)
at DependentPromiseActionsTest.testAsStringAsync(DependentPromiseActionsTest.java:295)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:85)
at org.testng.internal.Invoker.invokeMethod(Invoker.java:639)
at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:821)
at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1131)
at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:124)
at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:108)
at org.testng.TestRunner.privateRun(TestRunner.java:773)
at org.testng.TestRunner.run(TestRunner.java:623)
at org.testng.SuiteRunner.runTest(SuiteRunner.java:357)
at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:352)
at org.testng.SuiteRunner.privateRun(SuiteRunner.java:310)
at org.testng.SuiteRunner.run(SuiteRunner.java:259)
at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86)
at org.testng.TestNG.runSuitesSequentially(TestNG.java:1185)
at org.testng.TestNG.runSuitesLocally(TestNG.java:1110)
at org.testng.TestNG.run(TestNG.java:1018)
at com.sun.javatest.regtest.agent.TestNGRunner.main(TestNGRunner.java:94)
at com.sun.javatest.regtest.agent.TestNGRunner.main(TestNGRunner.java:54)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
at java.base/java.lang.Thread.run(Thread.java:831)