ADDITIONAL SYSTEM INFORMATION :
This is a documentation issue

A DESCRIPTION OF THE PROBLEM :
The sample code for handling buffer underflow during SSLEngine.wrap references the wrong buffer. It should reference "src" instead of "dst". I have annotated the snippet below:

   BUFFER_UNDERFLOW:
       int netSize = engine.getSession().getPacketBufferSize();
       // Resize buffer if needed.
       if (netSize > dst.capacity()) { ----> this should be src.capacity()
           ByteBuffer b = ByteBuffer.allocate(netSize);
           src.flip();
           b.put(src);
           src = b;
       }
       // Obtain more inbound network data for src,
       // then retry the operation.
       break;