Co-author some files

Signed-off-by: NathanDissoubray <nathan.dissoubray@rte-france.com>

Author: NathanDissoubray

diagram-util/src/main/java/com/powsybl/diagram/util/forcelayout/ForceLayout.java

@@ -51,6 +51,7 @@
  * The algorithm is taken from: https://github.com/dhotson/springy
  *
  * @author Mathilde Grapin {@literal <mathilde.grapin at rte-france.com>}
+ * @author Nathan Dissoubray {@literal <nathan.dissoubray at rte-france.com>}
  */
 public class ForceLayout<V, E> {
     private final Set<Spring> springs = new LinkedHashSet<>();

diagram-util/src/main/java/com/powsybl/diagram/util/forcelayout/geometry/Vector2D.java

@@ -9,6 +9,7 @@
 
 /**
  * @author Mathilde Grapin {@literal <mathilde.grapin at rte-france.com>}
+ * @author Nathan Dissoubray {@literal <nathan.dissoubray at rte-france.com>}
  */
 public class Vector2D {
     private double x;