optaplanner-examples/src/main/java/org/optaplanner/examples/vehiclerouting/domain/location/Location.java
public double getAngle(Location location) {
        // Euclidean distance (Pythagorean theorem) - not correct when the surface is a sphere
        double latitudeDifference = location.latitude - latitude;
        double longitudeDifference = location.longitude - longitude;
        return Math.atan2(latitudeDifference, longitudeDifference);
    }
public double getAngle(Location location) {
        // Euclidean distance (Pythagorean theorem) - not correct when the surface is a sphere
        double latitudeDifference = location.latitude - latitude;
        double longitudeDifference = location.longitude - longitude;
        return Math.atan2(latitudeDifference, longitudeDifference);
    }
The angle relative to the direction EAST.
@param location never null
@return in Cartesian coordinates