The new test just backported by JDK-8054022 to jdk11u-dev does not compile with jtreg 6.1:

/priv/jvmtests/output_openjdk11_dev_dbgU_linuxppc64le/jtreg/test/jdk/java/net/HttpURLConnection/HttpURLConnectionExpectContinueTest.java:32: error: package org.junit.jupiter.api does not exist
import org.junit.jupiter.api.AfterAll;
...
/priv/jvmtests/output_openjdk11_dev_dbgU_linuxppc64le/jtreg/test/jdk/java/net/HttpURLConnection/HttpURLConnectionExpectContinueTest.java:49: error: cannot find symbol
@TestInstance(TestInstance.Lifecycle.PER_CLASS)
...

/priv/jvmtests/output_openjdk11_dev_dbgU_linuxppc64le/jtreg/test/jdk/java/net/HttpURLConnection/HttpURLConnectionExpectContinueTest.java:313: error: cannot find symbol
    @Test
     ^
  symbol: class Test
  location: class HttpURLConnectionExpectContinueTest