Javadoc
Returns the so-called performance color. This color is actually a color between good -
average - bad color descriptors based on the values supplied. For example, if the actual
value is close to the good value, good color will be returned. Color is created based on a
linear gradient between two colors. It is possible that actual value is "better" than good
value, and in this case always the good color is returned. It is irrelevant if the good value
is higher or smaller that bad value, but it is important that they are not the same
(exception will be thrown in that case).