Bug when using the bold version of an otf font - maybe bad fullName computation in OTFFile

Overview
I get this message when using the bold version of Noto Sans CJK JP :
Font "Noto Sans CJK JP,normal,700" not found. Substituting with "Noto Sans CJK JP,normal,400".

Steps to reproduce

1. Use this xconf :

<fop version="1.0">
<use-cache>false</use-cache>
<renderers>
<renderer mime="application/pdf">
<fonts>
<!-- register all the fonts found in a directory -->
<directory recursive="true">path to font directory</directory>
</fonts>
</renderer>
</renderers>
</fop>

2. Set a valid path for "path to font directory", and set there the Noto Sans CJK JP fonts, that you can get from there :
https://noto-website-2.storage.googleapis.com/pkgs/NotoSansCJKjp-hinted.zip

3. Use the code from this page :
https://xmlgraphics.apache.org/fop/2.1/embedding.html

4. Use this "myfile.fo" as input :

<?xml version="1.0" encoding="ISO-8859-1"?>
<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
<!-- defines the layout master -->
<fo:layout-master-set>
<fo:simple-page-master master-name="first" page-height="29.7cm" page-width="21cm" margin-top="1cm" margin-bottom="2cm" margin-left="2.5cm" margin-right="2.5cm">
<fo:region-body margin-top="1cm"/>
<fo:region-before extent="1cm"/>
<fo:region-after extent="1.5cm"/>
</fo:simple-page-master>
</fo:layout-master-set>

<!-- starts actual layout -->
<fo:page-sequence master-reference="first">
<fo:flow flow-name="xsl-region-body">
<fo:block font-family="Noto Sans CJK JP" font-size="12pt" font-weight="bold">
Some special characters:
</fo:block>
</fo:flow>
</fo:page-sequence>
</fo:root>

Actual Results:
I get this message :
Font "Noto Sans CJK JP,normal,700" not found. Substituting with "Noto Sans CJK JP,normal,400".
And my text in the generated pdf is not bold.

Expected Results:
The message should not appear, and the text in the generated pdf should be bold.

Additional Information:
If I change the OTFFile.readName() method with this code:
@Override
protected void readName() throws IOException {
Object familyName = fileFont.getProperty("FamilyName");
if (familyName != null && !familyName.equals(""))

{ familyNames.add(familyName.toString()); fullName = fileFont.getName(); }

else

{ fullName = fileFont.getName(); familyNames.add(fullName); }

}

More precisely :
I replace
fullName = familyName.toString();
by
fullName = fileFont.getName();

it solves the bug.