Apply suggestions from code review

Co-authored-by: Sophie Frasnedo <sophie.frasnedo@rte-france.com>
Signed-off-by: Florian Dupuy <66690739+flo-dup@users.noreply.github.com>

Author: flo-dup

network-area-diagram/src/main/java/com/powsybl/nad/svg/DefaultEdgeRendering.java

@@ -258,8 +258,8 @@ private List<Double> calculateInsertedAngles(int[] nbInsertedAngles, double[] de
             }
             double extraSpace = deltaAngles[i] - Math.toRadians(slotAperture) * nbAnglesInDelta;
             double intraSpace = extraSpace / (nbAnglesInDelta + 1); // space between two added angles and between other edges and first/last angle
-            double angleStep = (anglesOtherEdges.get(i + 1) - anglesOtherEdges.get(i) - intraSpace) / nbAnglesInDelta;
-            double startAngle = anglesOtherEdges.get(i) + intraSpace / 2 + angleStep / 2;
+            double angleStep = intraSpace + Math.toRadians(slotAperture);
+            double startAngle = anglesOtherEdges.get(i) + intraSpace + Math.toRadians(slotAperture) / 2;
             IntStream.range(0, nbAnglesInDelta).mapToDouble(iLoop -> startAngle + iLoop * angleStep).forEach(insertedAngles::add);
         }
         return insertedAngles;