How the vertical space added by the height multiplier should be distributed over and under the text.
When a non-null height is specified, after accommodating the glyphs of the text, the remaining vertical space from the allotted line height will be distributed over and under the text, according to the leadingDistribution property. See the TextStyle class's documentation for an example.
Defaults to null, which defers to the paragraph's
final ui.TextLeadingDistribution? leadingDistribution;