I have an application using POI to open many pdf documents and it appears to freeze on some of them.
At first I thought it was password protection but it doesn't happen only to password protected pdf's 

The error is included in the attached.

Exception in thread "Consumer-2" java .lang.NoClassDefFoundErrro:  org/bouncycastle/jce/provider/BouncyCastleProvider
At org.pdfbox.pdmodel.PDDocument.openProtection(PDDocument.java:905)

I am looking at the code to catch the exception but I am puzzled why it locks at runtime and not propagate error and terminate application