Acrobat Reader error with Adobe Kozuka Mincho font

The Kozuka Mincho Pr6N R font cannot be embedded into PDF document.

How to repeat
1. Get FOP from trunk@1784735
2. Install Adobe Acrobat Reader DC Japanese language version.
3. Get Font from C:\Program Files (x86)\Adobe\Acrobat DC\Resource\CIDFont\KozMinPr6N-Regular.otf
4. Use my config file and generate the PDF, there is no error reported.
5. Open the PDF file in Acro-Reader, it will report the "cannot extract the embedded font" error.

Notes
1. When use the Noto Sans CJK JP and Kozuka Gothic Pr6N M fonts, there is no problem.
2. But NfMotoya Cedar Std W1 (Free Font, Regisration needed) and Morisawa A-OTF Shin Go Pro R are failed.
3. Read embedded stream by CFFParser, test_NotoSansCJKjp.pdf is ok, test_KozukaMinchoPr6NR.pdf is failed at reading CharStringIndex.
java.io.EOFException
at org.apache.fontbox.cff.DataInput.readUnsignedShort(DataInput.java:151)
at org.apache.fontbox.cff.CFFDataInput.readCard16(CFFDataInput.java:55)
at org.apache.fontbox.cff.CFFParser.readIndexDataOffsets(CFFParser.java:172)
at org.apache.fontbox.cff.CFFParser.readIndexData(CFFParser.java:193)
at org.apache.fontbox.cff.CFFParser.parseFont(CFFParser.java:456)
at org.apache.fontbox.cff.CFFParser.parse(CFFParser.java:141)

CFFParser#parseFont()
// charstrings index
DictData.Entry charStringsEntry = topDict.getEntry("CharStrings");
int charStringsOffset = charStringsEntry.getNumber(0).intValue(); // THIS VALUE IS NEGATIVE!!
input.setPosition(charStringsOffset);
byte[][] charStringsIndex = readIndexData(input);