PDFDebugger shows wrong hex view for image

Steps to reproduce the problem:

• open the file of PDFBOX-2188
• go to Root/Pages/Kids/[2]/Resources/Pattern/P2/Resources/XObject/Im1
• a CCITT encoded image will show up
• click on "Hex view"

expected:

• empty screen, or a hex view of the bytes of the image being displayed

got instead:

• a hex view with "JFIF". This is probably some JPEG image, no idea where it came from.