jdeps highlights the dependencies on JDK internal APIs. The sun.* and many of the com.sun.* API in the JDK are implementation specific classes and unsupported. They are subject to change/remove at any time in a future release [1]. The current way to find dependencies on JDK internal APIs is not the most quick and easy way. This is one way doing it:

$ jdk8/bin/jdeps -verbose:class -classpath <class-path-for-your-app> -include ".*" <your-application-jar> | \
      awk '/\^ *\-> .* JDK internal API/ { if (flag) { print classname; flag=0;} print $0; next;} $1 \!\~ /->/ { flag=1 classname=$0;}'

Providing a specific option to report JDK internal APIs would make it easier for developers to use.

[1] http://www.oracle.com/technetwork/java/faq-sun-packages-142232.html