get
Given a run of glyphs, return the associated horizontal adjustments. Adjustments are in "design units", which are integers relative to the typeface's units per em (see .getUnitsPerEm).
Some typefaces are known to never support kerning. Calling this with null, if it returns null then it will always return null (no kerning) for all possible glyph runs. If it returns int0, then it may return non-null adjustments for some glyph runs.
Return
adjustment array (one less than glyphs), or null if no kerning should be applied