Some tests in OpenJDK 8u refer to the COMPAT provider only available in JDK 9+:

     test/java/text/Format/DateFormat/DateFormatTest.java
     test/java/text/Format/ DateFormat/NonGregorianFormatTest.java
     test/java/text/Format/MessageFormat/LargeMessageFormat.java
     test/java/text/For mat/NumberFormat/NumberRegression.java
     test/java/text/Format/NumberFormat/NumberTest.java
     test/java/util/TimeZone/HongKong.java

See:
https://docs.oracle.com/javase/8/docs/technotes/guides/intl/enhancements.8.html