master
8382018: test/jdk/java/nio/file/spi/SetDefaultProvider.java leaves a directory in /tmp
8272477: Additional cleanup of test/jdk/java/nio/file/spi/SetDefaultProvider.java
8283335: Add exists and readAttributesIfExists methods to FileSystemProvider
8383185: [21u] Backport of JDK-8382925 causes test failure in SetDefaultProvider