I get the error below, but I can find the package in rt.jar. I can see the JDK being used from Project Structure. I'm not sure what's missing.
Error:(6, -1) Play 2 Compiler:
C:\user\projects\portal\app\com\example\security\cert\X509Cert.java:6: package sun.security.pkcs10 does not exist
import sun.security.pkcs10.*;
C:\user\projects\portal\app\com\v\security\cert\GenerateCSR.java:75: cannot find symbol
This is not an intellij issue.
You need to compile with the -XDignore.symbol.file option. Some internal packages
are hidden by default unless you add this option to javac.
https://bugs.openjdk.java.net/browse/JDK-7141442
Also the comment of user @user180100 is relevant and important.
The sun.* packages are not part of the supported, public interface.
A Java program that directly calls into sun.* packages is not guaranteed to work on all Java-compatible platforms. In fact, such a program is not guaranteed to work even in future versions on the same platform.