JDK-8268801 has introduced src/java.base/share/classes/sun/security/util/KnownOIDs.java, so the copied version for tests is no longer needed.
Backport introducing the new file: https://github.com/openjdk/jdk11u/commit/256c17f85328f5548b84b67b609afad9b89f026a
Test version was introduced with backport of JDK-8153005:
https://github.com/openjdk/jdk11u-dev/commit/596cc70c9724b31ffee454b7a21ecefec731c4ba