Proguard rules missing

[SammyOdenhoven]

Are there any Proguard rules that need to be added when using this library? I'm seeing warnings related to Flexmark, like:
Warning: com.vladsch.flexmark.util.ImageUtils: can't find referenced class javax.swing.ImageIcon

[ugurcany]

Here are the proguard rules you need to add:

-dontwarn java.awt.**
-dontwarn javax.swing.**
-dontwarn javax.imageio.**