Under JDK-8153362:
Add javac -Xlint warning to list exposed types which are not accessible

A new lint for javac is developed that warns about exported elements that refer to types that are potentially inaccessible to the client of the API (like package private or not exported types).

For jdk.security.jgss, the warnings are:
---
.../jdk9/jdk/src/jdk.security.jgss/share/classes/com/sun/security/jgss/ExtendedGSSContext.java:42: warning: [exports] class GSSContextImpl in module java.security.jgss may not be visible to all clients that require this module
    static class ExtendedGSSContextImpl extends GSSContextImpl
                                                ^
.../jdk9/jdk/src/jdk.security.jgss/share/classes/com/sun/security/jgss/ExtendedGSSContext.java:45: warning: [exports] class GSSContextImpl in module java.security.jgss may not be visible to all clients that require this module
        public ExtendedGSSContextImpl(GSSContextImpl old) {
                                      ^
error: warnings found and -Werror specified
.../jdk9/jdk/src/jdk.security.jgss/share/classes/com/sun/security/jgss/ExtendedGSSCredential.java:38: warning: [exports] class GSSCredentialImpl in module java.security.jgss may not be visible to all clients that require this module
    static class ExtendedGSSCredentialImpl extends GSSCredentialImpl
                                                   ^
.../jdk9/jdk/src/jdk.security.jgss/share/classes/com/sun/security/jgss/ExtendedGSSCredential.java:41: warning: [exports] class GSSCredentialImpl in module java.security.jgss may not be visible to all clients that require this module
        public ExtendedGSSCredentialImpl(GSSCredentialImpl old) {
                                         ^
1 error
4 warnings
---

The lint will be disabled for jdk.security.jgss. Please check if the warnings can be fixed, or needs to be suppressed. Maybe the ExtendedGSSContextImpl and ExtendedGSSCredentialImpl classes are not intended to be public (they are implicitly public, as they are declared in an interface)?

Thanks.