How can I add transparency circle around to the current location of the google map?

Question

This is my circle part of the code,Tell me how to further implement this code??What I want to add to get transparency shape of color??

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Circle circle = map.add Circle(new CircleOption())
.center(new LatLng(6.97852,79.2565)
.radius(10000)
.strokeColor(Color.RED)
.fillColor(Color.BLUE));