protected int getCenterLocation(int contextLocation, int contextLength, int placementLength) {
		return contextLocation + (contextLength - placementLength) / 2;
	}
Determines the placementLocation such that the midpoint of the context and the midpoint
of the placement are at the same point.  Location and Length can either be an x value and
width or a y value and height.

@param contextLocation the x or y value of the context, depending on if we are doing the
       horizontal or vertical midpoint
@param contextLength the corresponding width (if dealing with x/horizontal midpoint) or
       height (if dealing with y/vertical midpoint)
@param placementLength the corresponding height or width of the placement
@return the placement location (again x or y value)
Ghidra/Framework/Docking/src/main/java/docking/widgets/shapes/PopupWindowPlacer.java