StackWalker.getCallerClass() skips all @Hidden & java.lang.invoke methods when looking for caller. If a library uses SW.gCC to implement caller-sensitive logic, it can cause problems.

java.lang.invoke, when constructing a method handle for @CallerSensitive method, binds it to lookup context by attaching a VMAC w/ lookup class as a host class (see [1] for details). During invocation, it puts a @Hidden frame on stack which represents original caller context.

SW.gCC() filters out that frame, so a library sees the caller of method handle instead.

For example, in methodHandleGetCallerClass() [2] if a method handle leaks and it is invoked from another context, the bound context will be ignored if SW.gCC is used (R.gCC correctly returns the class MH is bound to).

Reflection.getCallerClass() is more conservative when filtering frames [3].

[1] http://hg.openjdk.java.net/jdk9/dev/jdk/file/248c2f34cc1f/src/java.base/share/classes/java/lang/invoke/MethodHandleImpl.java#l1167

[2] http://hg.openjdk.java.net/jdk9/dev/jdk/file/248c2f34cc1f/test/java/lang/StackWalker/GetCallerClassTest.java#l129

[3] http://hg.openjdk.java.net/jdk9/jdk9/hotspot/file/e3ca323dfe1b/src/share/vm/oops/method.cpp#l1122: