I found uses of WeakGlobalRefs in the following files.

./awt_Font.h(250): /* JNI WeakGlobalRef to java.awt.Font object */
./awt_Font.cpp(143): m_javaFont = env->NewWeakGlobalRef(javaFont);
./awt_Font.cpp(168): env->DeleteWeakGlobalRef(m_javaFont);
./awt_Graphics.cpp(350): env->DeleteWeakGlobalRef(m_javaObject);
./awt_Graphics.cpp(356): m_javaObject = env->NewWeakGlobalRef(obj);
./awt_Cursor.cpp(41): jCursor = env->NewWeakGlobalRef(jCur);
./awt_Cursor.cpp(54): jCursor = env->NewWeakGlobalRef(jCur);
./awt_Cursor.cpp(89): env->DeleteWeakGlobalRef(jCursor);
./awt_Robot.cpp(24): m_peerObject = env->NewWeakGlobalRef(peer);
./awt_Robot.cpp(36): env->DeleteWeakGlobalRef(m_peerObject);
./Win32SurfaceData.cpp(309): wsdo->peer = env->NewWeakGlobalRef(peer);
./Win32SurfaceData.cpp(1210): env->DeleteWeakGlobalRef(wsdo->peer);

awt_Font looks okay
awt_Graphics has been removed from the master
Win32SurfaceData belongs to 2D
awt_Robot and awt_Cursor belong to AWT