Looks like the Compact Strings work inadvertently introduced a
dependency on sun.misc.Unsafe. ( just temporary confusion with
having two Unsafes until the jdk.unsupported module is defined )

diff --git a/src/java.base/share/classes/sun/nio/cs/StringUTF16.java b/src/java.base/share/classes/sun/nio/cs/StringUTF16.java
--- a/src/java.base/share/classes/sun/nio/cs/StringUTF16.java
+++ b/src/java.base/share/classes/sun/nio/cs/StringUTF16.java
@@ -25,8 +25,8 @@

package sun.nio.cs;

-import static sun.misc.Unsafe.ARRAY_BYTE_BASE_OFFSET;
-import static sun.misc.Unsafe.ARRAY_BYTE_INDEX_SCALE;
+import static jdk.internal.misc.Unsafe.ARRAY_BYTE_BASE_OFFSET;
+import static jdk.internal.misc.Unsafe.ARRAY_BYTE_INDEX_SCALE;

class StringUTF16 {

@@ -35,5 +35,5 @@
                              ARRAY_BYTE_BASE_OFFSET + ARRAY_BYTE_INDEX_SCALE * index * 2L);
    }

- private static final sun.misc.Unsafe unsafe = sun.misc.Unsafe.getUnsafe();
+ private static final jdk.internal.misc.Unsafe unsafe = jdk.internal.misc.Unsafe.getUnsafe();
}