Something

BYTEARRAY pRawMsgBytes = Jbni_newByteArray (rawMsg.Size());
bytesRead = rawMsg.Read (pRawMsgBytes->data, rawMsg.Size());

OR

uint32 size = rawMsg.Size();
BYTEARRAY pRawMsgBytes = Jbni_newByteArray (size);
bytesRead = rawMsg.Read (pRawMsgBytes->data, size);