This is an Expression representation of "fill-color".
The color of the filled part of this layer. This color can be specified as
rgba with an alpha component and the color's opacity will not affect the opacity of the 1px stroke, if it is used.
This is an Expression representation of "fill-pattern".
Name of image in sprite to use for drawing image fills. For seamless patterns, image width and height must be a factor of two (2, 4, 8, ..., 512). Note that zoom-dependent expressions will be evaluated only at integer zoom levels.