Return the type of embedded font: one of the values "TrueType", "OpenType", "Type1", "Compact",
"MultipleMaster" or "Type3". Unembedded fonts return "Unembedded". Fonts that are created but
never used in the PDF to display any glyphs have a type "Unused"
Return a BitSet containing all the Unicode codepoints
that are used by this font in the PDF. If a font displays
glyphs that cannot be resolved to a Unicode character, this
set will return null, but that doesn't necessarily mean it's
not been applied to the PDF